Review ArticlePolymeric Gas-Separation Membranes for Petroleum Refining
Yousef Alqaheem Abdulaziz Alomair Mari Vinoba and Andreacutes Peacuterez
Petroleum Research Centre Kuwait Institute for Scientific Research Ahmadi Kuwait
Correspondence should be addressed to Yousef Alqaheem yqaheemkisredukw
Received 8 November 2016 Accepted 23 January 2017 Published 19 February 2017
Academic Editor Eliane Espuche
Copyright copy 2017 Yousef Alqaheem et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
Polymeric gas-separation membranes were commercialized 30 years agoThe interest on these systems is increasing because of thesimplicity of concept and low-energy consumption In the refinery gas separation is needed in many processes such as natural gastreatment carbon dioxide capture hydrogen purification and hydrocarbons separations In these processes the membranes haveproven to be a potential candidate to replace the current conventional methods of amine scrubbing pressure swing adsorptionand cryogenic distillation In this paper applications of polymeric membranes in the refinery are discussed by reviewing currentmaterials and commercialized units Economical evaluation of these membranes in comparison to traditional processes is alsoindicated
1 Introduction
Implementation of membrane systems is growing in theindustry because of the unique features that the membranecan provide [1] Compared to other separation processes themembrane is simple to install and requires minimum super-vision [2] Furthermore it occupies less space and does nothave moving parts thus it needs almost no maintenance [3]In addition it operates with low energy and is considered asan environmentally friendly technology because it does notemit gases nor work with solvents [4] The membrane is alsoeasy to scale up for better commercialization [5]
Based on the material the membranes are categorizedinto metallic inorganic and polymeric [6] Metallic mem-branes made of platinum or palladium have excellent per-formance but the cost of precious metals greatly influencesthe membrane selection Inorganic membranes are goodalternatives and they have better chemical stability with lowerfabrication cost [7] Nevertheless high temperature of 200 to900∘C is needed to operate inorganic membranes [2] Nowa-days polymeric membranes dominate the industry becauseof the outstanding economy and competitive performance[8] The membranes can be operated at ambient temperatureand they have good mechanical and chemical properties [9]
Revolution of polymeric membranes started in 1960swhen Loeb and Sourirajan developed a membrane made
from cellulose acetate for water desalination by reverseosmosis [10] The thin membrane of 02 120583m was supportedon a porous substrate and it was capable of convertingseawater to potable water They found later that celluloseacetate membrane can be used for gas separation as well [11ndash13] Afterwards Stern et al in 1969 studied the diffusion ofdifferent gases such as helium and nitrogen in polyethylenemembrane at high temperatures and this opened the oppor-tunity for more research in this area [14]
The first large scale membrane was developed by Permea(Air Products) in 1980 for separation of hydrogen Thehollow fiber membrane was made of polysulfone and itwas designed to separate hydrogen from methane [15 16]In 1983 Cynara and Separex also manufactured a celluloseacetate membrane but for carbon dioxide separation frommethane [16] A few years later nitrogen production fromair using membranes was introduced [17] The applicationsof membrane were expanded hereafter to cover removal ofhydrogen sulfide from methane removal of volatile organiccompounds (VOCs) from air oxygen enrichment and airdehydration [2] Today the membrane is used in the refin-ery to purify natural gas by removing acid gases such ashydrogen sulfide and carbon dioxide from methane [17] Itis also implemented in many hydrotreatment processes torecover hydrogen from hydrogen sulfide [18] Adjustmentof hydrogen-to-carbon monoxide ratio in syngas to meet
HindawiInternational Journal of Polymer ScienceVolume 2017 Article ID 4250927 19 pageshttpsdoiorg10115520174250927
2 International Journal of Polymer Science
Table 1 Processes where membrane technology is implemented[25ndash27]
VOCsAirH2 from other gasesCH4 from other gasesCO2 from other gases
the requirement of petrochemical feedstock can be doneusing the membranes Oxygen enrichment in furnaces forbetter oxidation is also practiced in many processes [19]Applications of themembrane for petroleum industry and thecorresponding separation gases are presented in Table 1 Inthis review uses of these membranes are discussed in detailincluding the membrane materials commercialized systemsand comparison with traditional separation methods In thefollowing section transport mechanism of these membranesis given
2 Transport Mechanism inPolymeric Membranes
For gas applications the polymeric membranes are usuallymade from a thin dense layer [17] To enhance the mechan-ical properties the dense layer is supported on a poroussubstrate [20] The widely accepted theory for the transportmechanism is based on solution diffusion model [21] Thismodel consists mainly of three steps (1) absorption ofmolecules on the polymer surface (2) diffusion of moleculesinside the polymer and (3) desorption of molecules onthe low-pressure side [9] The driving force is the pressuregradient across the membranes and each compound hasdifferent absorption and diffusion rate The membrane per-formance can be evaluated by themeasuring the permeabilityand selectivity of gases The permeability is the product ofabsorption and diffusion coefficients as follows
119875 = 119870119894119863119894 (1)
where 119870119894 is the sorption coefficient and 119863119894 is the diffusioncoefficientThe unit of permeability is Barrer that equals 10minus10(cm3cmsdotssdotcmHg) Experimentally the permeability can becalculated based on the flux [22]
119875 = 119869Δ119897
Δ119875 (2)
where 119869 is the flux (volume flow rate per unit area) Δ119897 is themembrane thickness andΔ119875 is the pressure difference across
the membrane On the other hand selectivity (120572119894119895) refers topermeability ratio of two gases
120572119894119895 =119875119894119875119895 (3)
The polymers are classified based on the structure to rubberyand glassy Rubbery polymers have the ability to return totheir original shape once stretched while glassy ones do not[23] Furthermore rubbery polymers tend to have higherpermeation but lower selectivity and this is because thetransport mechanism is controlled by absorption rather thandiffusion [24] Conversely glassy membranes have higherselectivity but low permeation because they are diffusionlimited This indicates that there is a trade-off between per-meability and selectivity and it is difficult to have a polymerhaving both characteristics In the following section uses ofmembranes for hydrogen sulfide separation carbon dioxiderecovery hydrogen purification air separation gas dehydra-tion organic vapors recovery and liquefied petroleum gas arediscussed in detail
3 Removal of Hydrogen Sulfide
Hydrogen sulfide is well known for its rotten-egg smell evenin low concertation of parts per billion (ppb) [28] The gas isemitted naturally from volcanoes and can be formed duringthe decomposition of organic matters [29] The gas is alsofound in natural gas and it is called sour gas if hydrogensulfide concertation is above 4 ppm [30] Because the gas iscorrosive and can cause damage to pipelines the sale gasshould not have more than 4 ppm of hydrogen sulfide and2mol of carbon dioxide [31] Hydrogen sulfide is a man-made gas too and dehydrosulfurization process (to removesulfur compounds from fuel) is considered as themain source[32]
31 Current Technologies There are threemethods for hydro-gen sulfide removal (1) physicalchemical absorption (2)adsorption and (3) membranes Chemical absorption byamine scrubbing is the dominant process for hydrogen sulfideseparation from natural gas [33] The process can removecarbon dioxide as well and the treated stream can have lowerthan 4 ppm of hydrogen sulfide The technology is based onthe absorption of hydrogen sulfide and then the reaction withamine by [34]
2RNH2 +H2Slarrrarr (RNH3)2 S (4)
(RNH3)2 S +H2Slarrrarr 2RNH3HS (5)
The solvent (mainlymonoethanolamineMEA) can be regen-erated by increasing the temperature or reducing the pres-sure In spite of the high efficiency of amine scrubbing thereare some drawbacks which are (1) high capital investment(2) massive energy required to regenerate the solvent (3)oxidation of amines which can cause foaming or floodingand (4) requirement of special alloys to withstand the solventcorrosivity [35ndash39]
International Journal of Polymer Science 3
Physical absorption by methanol is another way to rem-ove hydrogen sulfide from natural gas The process is calledRectisol (licensed by Linde Group and Air Liquide) and itcan remove carbon dioxide carbonyl sulfide and mercap-tans [40] At lower temperature the absorption capacity ofmethanol increases and that is why the process operates atminus30 to minus70∘C [41] It should be mentioned that methanolcan be replaced with other solvents like polyethylene glycol(Selexol process) or potassium carbonate but methanolhas better absorption capacity and higher regeneration rate[35 37 42 43] Compared to amine scrubber methanolabsorption has better removal efficiency but at the expenseof capital and operating costs [39]
Adsorption by carbon molecular sieve (CMS) is anothertechnique to separate hydrogen sulfide from methane Theconcept is based on adsorption of hydrogen sulfide on thecarbon surface at high pressure [44] Activated carbon haslarge surface area with high porosity and the capacity canreach 150mg of hydrogen sulfide to one gram of carbon[45]The desorption (regeneration) step can be performed byreducing the pressure or increasing the temperature to 288ndash316∘C [46] Unfortunately CMS cannot be used to removehigh content of hydrogen sulfide of more than 15mol dueto the lower adsorption capacity compared to amine scrubber[47] Furthermore carbon suffers from lowmechanical prop-erties making it unstable at high content of hydrogen sulfide[48]
The membrane technology can provide an alternativesolution for removal of hydrogen sulfide Unlike aminescrubbing or methanol absorption the membrane does notrequire a solvent to operate and this will cut down the costof purchasing and disposing of the solvent The membranehas also an advantage over CMS as it can operate withfeeds containing up to 16mol of hydrogen sulfide [31] Inthe following section performances of different membranematerials are reviewed for removal of hydrogen sulfide fromnatural gas
32 Membrane Materials Cellulose acetate is widely usedfor hydrogen sulfide removal from natural gas [49] Thismaterial is extracted from wood pulp and it has a hydrogensulfide permeability of 213 Barrer with hydrogen sulfide tomethane selectivity (120572H2SCH4) of 194 [50] The material wastested with natural gas containing heavy hydrocarbons andunexpectedly the selectivity dropped significantly due to thepenetration of sorption sites [50 51]
Polydimethylsiloxane (PDMS) gives a superior hydrogensulfide permeability of 2750 Barrer and this high permeabil-ity is related to the rubbery structure but at the expense ofselectivity of 098 [17] To enhance the membrane durabilityunder the harsh environment of hydrogen sulfide cross-linking was introduced [52] It helps in reducing the poly-meric chain mobility and this increases the glass transitiontemperature As a result resistance to plasticization andaging is improved [17] In addition cross-linking generallyaffects the segmental mobility of the polymer making thediffusion process rely more on the size and shape of themolecule to be separated and this improves the selectivity butreduces permeability [53] In 1997 Chatterjee et al developed
a copolymer consisting of ether urethane and urea and itwas prepared by the two-step polycondensation techniqueIn the first step methylene bis-(4-phenyl isocyanate) (MDI)is added to polyethylene glycol (PEG) with the use ofdimethyl sulfoxide (DMSO) as a solvent In the secondstep a chain extender (12-diaminoethane) was added tothe solution to form poly(ether-urethane-urea) (PUU) [50]Unlike membranes made of single polymer PUU consists oftwo segments soft and hard The hard segment has a glassystate and acts as a filler while the soft segment is rubberygiving the membrane elasticity and flexibility [54] PUU wastested for hydrogen sulfide separation frommethane and thepermeability was 199 Barrer with outstanding selectivity of 74[55]
Pebax is another copolymer made of polyether and poly-amide The term ldquoPebaxrdquo stands for polyether-block-amideand it was manufactured by Arkema [56] There are manygrades of Pebax and each grade depends on the concentrationof polyether and polyamide For example the popular Pebax1074 is made from 73wt polyether and 27wt polyamide[57] Hydrogen sulfide permeability of this material reached888 Barrer with selectivity of 21 [50] Permeability andselectivity of various membrane materials is given in Table 2The choice of material depends strongly on the compositionof the feed gas and whether permeability or selectivity is thefirst priority
33 Case Studies and Economical Evaluation MembraneTechnology and Research (MTR) is one of the companiesfor manufacturing gas-separation membranes SourSep (byMTR) is a membrane system to convert sour gas to sweetgas by the removal of hydrogen sulfide and it is expected tobe based on Pebax The unit was installed in an oil well in aremote area to treat wellhead gas so it can be used as a fuel[26] Indeed the system reduced hydrogen sulfide contentfrom 3400 ppm to less than 100 ppm The feed pressure wasat 51 bar and volume flow rate was 2001Nm3h Compared toamine scrubber themembrane system achieved lower capitaland operating costs The capital cost covers the membranematerial frame heat exchanger and vacuum pump whileoperating cost refers to energy used by compressors andpumps [17] FuelSep is another systemdeveloped byMTRanddesigned tomeet the quality of fuel gas by removing hydrogensulfide and other impurities such as carbon dioxide nitrogenand heavy hydrocarbons [2]
Universal Oil Products (UOP) Separex membrane isbased on cellulose acetate and designed to treat gases con-taining hydrogen sulfide up to 20mol [63] The system wascommercialized for nearly 30 years The system was installedin an off-shore gas reservoir containing 15mol of hydrogensulfide The feed volume was 588586Nm3h of gas at 92barThemembrane was capable of reducing hydrogen sulfidecontent to 70 ppm in the treated gas
An economical study was conducted by Bhide and Sternfor natural gas treatment using membranes and aminescrubbing [64] The membranes were based on celluloseacetate and content of hydrogen sulfide varied from 01to 1mol The feed also contained carbon dioxide of 5 to40mol Feed flow rate was 41201Nm3h at 54 bar The
4 International Journal of Polymer Science
Table 2 Permeability and selectivity of different polymeric membranes for removal of hydrogen sulfide from natural gas
processing cost (defined as the capital and operating costsover production volume) was calculated to achieve less than4 ppm of hydrogen sulfide and 2mol of carbon dioxide Itwas found that the processing cost in a membrane systemis a function of the concentration of hydrogen sulfide andcarbon dioxide the more the content the higher the costbut in amine scrubbing the processing cost was dependent oncarbon dioxide content only For a stream containing 1molhydrogen sulfide and 30mol carbon dioxide the processingcost for a membrane system was 487 times 10minus7 $(Nm3h) com-pared to 634 times 10minus7 $(Nm3h) for amine absorptionTherefore the use of membrane resulted in 23 reductionin processing cost However if the feed was changed to21mol carbon dioxide and 5000 ppm hydrogen sulfideboth systems had a processing cost of 487 times 10minus7 $(Nm3h)Amine scrubbing showed lower processing cost of 199 times10minus7 $(m3h) if the feed contained 5 carbon dioxide and1000 ppm hydrogen sulfide while the membrane gives 354 times10minus7 $(Nm3h)
4 Carbon Dioxide Capture
The atmosphere consists before of 315 ppm carbon dioxide(1955 reading) but because of the transportation and indus-trial activities the content is increased to 390 ppm causingglobal warming and increase in the climate temperature [65]The petroleum industry accounts for 8 of carbon dioxideemission and in order to reduce the impact carbon capturefrom flue gases is necessary [66]
In the refinery separation of carbon dioxide is requiredin the following processes natural gas treatment syngas pro-duction (hydrogen and carbon monoxide) and combustionToday wells are injected with a high-pressure carbon dioxidestream to enhance the oil recovery and this results in pro-duction of natural gas with high amounts of carbon dioxide[67] Removal of this carbon dioxide is essential because thegas is corrosive and can damage pipelines [68]Themaximum
content of carbon dioxide in commercial natural gas shouldnot exceed 2mol [31] Furthermore the flue gases of mostcombustion processes (furnaces) have amounts of carbondioxide and nitrogen Carbon dioxide capture is necessarilybefore releasing this gas to the atmosphere [69]
41 Current Technologies Most of the techniques for hydro-gen sulfide removal work as well for carbon dioxide becauseboth gases are polar The dominant method for carbon diox-ide removal from natural gas is still amine scrubbing [34]The process can remove bulk quantities of carbon dioxideand the final stream can have as low as 50 ppm of carbondioxide [39] Physical absorption by water polyethyleneglycol methanol and potassium carbonate is possible toseparate carbon dioxide In water absorption the gas entersa packed tower where carbon dioxide dissolves in waterand the concentrated stream is stripped by air to generatecarbon dioxide back and water is recycled The process iscost effective because water is readily available however therecirculated water can cause fouling therefore special pipingis needed [70] Polyethylene glycol (PEG) on the other handhas better selectivity compared to water and is considered as anoncorrosive solvent [43] The drawback of using PEG is thelow regeneration rate [43]
Hot potassium carbonate is efficient for removing largeamounts of carbon dioxide The process can also removesmall amounts of hydrogen sulfide The mechanism is basedon the reaction of carbon dioxide with potassium carbonatesolution [35]
K2CO3 + CO2 +H2Olarrrarr 2KHCO3 (6)
The carbon dioxide-enriched stream enters an absorberwhere it flows in a counter-current with a hot potassiumcarbonate solution at 110∘C [71] The solution is then sent toa flash drum where most of the acid gas will be removeddue to the reduction of the pressure To regenerate thesolvent it is sent to a stripper that operates at 120∘C and
International Journal of Polymer Science 5
Table 3 Current technologies for carbon dioxide separation
(i) Achieves gt99 of CO2 capture(ii) Produces liquefied CO2 for easier storage
(i) Economical only if the feed contains 50ndash70 CO2(ii) Higher pressure is required to avoid CO2 sublimation
Membranes(i) Requires minimum supervision(ii) Can remove H2S and H2O as well(iii) Long-operating life (gt5 years)
(i) High capital cost(ii) Pretreatment is required to remove particulates and some inhibitors
atmospheric pressure Unfortunately potassium carbonatehas lower sorption properties compared to amine and it ishighly corrosive [37 42]
Methanol can also be used for physical absorption ofcarbon dioxide and it has the highest selectivity compared toother solvents [39] The solvent can be regenerated by eitherreducing the pressure or increasing the temperature [40]Thefinal stream can have very low amounts of carbon dioxideof 10 ppm which is more efficient than amine scrubbingThe only disadvantage of this process is the high capitalinvestment [39]
Pressure swing adsorption (PSA) is another techniquefor carbon dioxide separation Unlike previous methodsPSA does not require a solvent The gas passes at a highpressure through a bed of activated carbon (also known ascarbon molecular sieve) and due to the difference in polarityadsorption of carbon dioxide will take place [72] The bedcan be regenerated by reducing the pressure to vacuumThe technique has an excellent separation performance andthe gas can have more than 90 methane purity and it isexpected to run for three years [73] Other PSA materialsare zeolite and alumina Disadvantages of this system arethe extensive energy for pressure cycle and low adsorptioncapacity compared to amine scrubbing [74]
Cryogenic distillation at very low temperature of minus84∘Cis efficient for carbon dioxide removal Because of the lowtriple point of carbon dioxide of minus57∘C at atmosphericpressure carbon dioxide will not have a liquid state and willsolidify directly [75] Therefore the distillation should takeplace at a pressure above 5 bar to overcome the triple pointlimitation otherwise carbon dioxide will cause blockageThe technology is used to liquify and produce high qualitystreams of carbon dioxide For the process to be economicalthe feed should contain 50 to 70 carbon dioxide and this isbecause of the high capital and operating costs of cryogenicdistillation [73] Unfortunately most of the refinery streamsdo not have that concentration of carbon dioxide [72]
In comparison with the above-mentioned the mem-branes have a unique feature as they can remove carbondioxide along hydrogen sulfide and water with one step [7677] In addition to low operating energy the membrane has along life and it can be operated continuously for at least 5 years
[78] However the operating life is greatly affected if partic-ulates were presented in the feed therefore pretreatment isneeded Table 3 shows the advantages and disadvantages ofdifferent methods for carbon dioxide capture
42 MembraneMaterials Removal of carbon dioxide startedwhen Robb studied in 1968 the diffusion of gases in PDMSmembrane [61] The work was expanded in 1989 when Sterndetermined the permeability coefficient of gases at highertemperature [17] CO2-permeable membranes are similar tothose that permeate hydrogen sulfide but the permeabil-ity differs due to the difference in sorption and diffusioncoefficients between carbon dioxide and hydrogen sulfideThe state-of-the-art materials for carbon dioxide separationare cellulose acetate polyamide polyimide and Pebax Asshown inTable 4 cellulose acetate has the lowest permeabilityof 24 Barrer but yet the selectivity of carbon dioxide tomethane (120572CO2CH4) reached 25 [25 50] Unfortunately pre-sence of heavy hydrocarbons in the feed caused a sig-nificant drop in the selectivity therefore cellulose acetatewas not suitable for fuel gas separation [50] Polyimideson the other hand show better thermal and chemical sta-bilities compared to cellulose acetate [2] These polymersare made from diacid with diamine in amic acid inter-mediate [79] Matrimid 5218 is a polyimide containingphenylindane group and it gives carbon dioxide permeabil-ity of 85 Barrer [1 80] This polymer shows outstandingselectivity of 28 and 367 for carbon dioxide to methane(120572CO2CH4) and carbon dioxide to nitrogen (120572CO2N2) respec-tively [81 82] Carbon dioxide permeability of polyimidecan be further enhanced by the introduction of fluo-ride Fluorinated polyimides are made using 22-bis(34-di-carboxyphenyl)hexafluoropropanedianhydride (6FDA) andthe permeability can be boosted to 456 Barrer [83 84]Copolymers like PUUand Pebax show also high permeabilityof 145 and 212 Barrer respectively [85 86] The rubberypolymer PDMS has an excellent permeability of 4000 Barrerbut the lowest carbon dioxide selectivity of 26 as given inTable 4
43 Commercial Units and Economical Evaluation Thelargest CO2-removal unit is manufactured by Cynara
6 International Journal of Polymer Science
Table 4 Permeability and selectivity of different polymers for carbon dioxide removal
(NATCO Group) for natural gas sweeting in an off-shorearea in Thailand The hollow fiber membrane is based oncellulose triacetate and capable of handling 830000Nm3h[25] Another system was installed to treat 120000Nm3h ofgas and it reduced carbon dioxide content from 80 to lessthan 10 [77 93]
Polaris membrane (made by MTR) was installed aftermethane-reforming unit and it successfully increased carbondioxide concentration from 20mol in the tail gas to morethan 90mol [26] The stream was used afterwards for wellinjection to enhance oil recovery Polaris membrane can alsotreat flue gases with excellent selectivity (120572CO2N2) of 50 [94]
UOP membranes are based on cellulose acetate and wereinstalled in Pakistan in 1995The systemworked continuouslyfor 12 years to cut down carbon dioxide concentration from65 to 2mol [63] The system was designed to process311950Nm3h of gas at 58 bar
UBE on the other hand developed a robust membrane forbetter stability under feed impurities The system is based onpolyimide membrane and it can work without any drop inperformance under the presence of 3mol hydrogen sulfidefull water saturation and heavy hydrogen carbons of C5+[95]
An economical study was done by Peters et al to comparethe membrane system with amine scrubbing for natural gaspurification [96] The feed gas contained 95mol CO220 ppm H2S 10 ppm H2O and 724mol CH4 and theremaining for C2 to C6 The operating conditions were 60∘Cand 90 bar Results show that both technologies achievedthe sale gas specification of 4 ppm H2S and 2mol CO2however the treated gas by amine has better carbon dioxidepurity compared to themembrane but this was at the expenseof the capital investment It was concluded that themembranetechnology was still a better choice due to the environmentalissue related to solvent disposal
Another economical evaluation was performed by He etal and it confirmed that the membrane can replace aminescrubbing for natural gas treatment containing 10mol
carbon dioxide and lower [97] Natural gas processing cost bythe membrane system was 000573 $Nm3 which was 104less than amine scrubbing
5 Hydrogen Recovery
Hydrogen is a key element for many processes in the refinerysuch as hydrocracking and hydrotreating In hydrocrackinghydrogen is used to convert large hydrocarbons into smallerones in presence of a catalyst while in hydrotreating hydro-gen is used to remove sulfur compounds from fuels in theform of hydrogen sulfide [98] Furthermore hydrogen is afeedstock for many industries like ammonia synthesis andmethanol production [99]
Hydrogen is produced in the refinery by steam-methanereforming (SMR) where methane reacts with water to pro-duce hydrogen and carbon monoxide The produced gas iscalled syngas and hydrogen yield can be further increasedby the reaction of carbon monoxide with water to formhydrogen and carbon dioxide [100]
In petroleum industry hydrogen separation can be prac-ticed in the following processes (1) to recover some hydrogenduring natural gas production (2) to adjust hydrogen-to-carbon monoxide ratio (H2CO) in syngas (3) to recyclepart of hydrogen from hydrocracker and hydrotreatment tailgases (4) to separate hydrogen from nitrogen in ammoniaplant and (5) to purify hydrogen so it can be used as afeedstock for other industries [102ndash104] Content of hydrogenin refinery off-gases is given in Table 5
51 Current Technologies Mainly there are three methodsto separate hydrogen from gas mixtures (1) cryogenic dis-tillation (2) PSA and (3) membrane system The selectionof technology depends on feed composition product purityproduct flow rate reliability turndown and last but not leastcapital and operating costs Comparison between the threetechnologies is given in Table 6 As indicated the membranehas a better capability to treat a wider range of hydrogen from
International Journal of Polymer Science 7
Table 5 Hydrogen composition in refinery off-gases [101]
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
VOCsAirH2 from other gasesCH4 from other gasesCO2 from other gases
the requirement of petrochemical feedstock can be doneusing the membranes Oxygen enrichment in furnaces forbetter oxidation is also practiced in many processes [19]Applications of themembrane for petroleum industry and thecorresponding separation gases are presented in Table 1 Inthis review uses of these membranes are discussed in detailincluding the membrane materials commercialized systemsand comparison with traditional separation methods In thefollowing section transport mechanism of these membranesis given
2 Transport Mechanism inPolymeric Membranes
For gas applications the polymeric membranes are usuallymade from a thin dense layer [17] To enhance the mechan-ical properties the dense layer is supported on a poroussubstrate [20] The widely accepted theory for the transportmechanism is based on solution diffusion model [21] Thismodel consists mainly of three steps (1) absorption ofmolecules on the polymer surface (2) diffusion of moleculesinside the polymer and (3) desorption of molecules onthe low-pressure side [9] The driving force is the pressuregradient across the membranes and each compound hasdifferent absorption and diffusion rate The membrane per-formance can be evaluated by themeasuring the permeabilityand selectivity of gases The permeability is the product ofabsorption and diffusion coefficients as follows
119875 = 119870119894119863119894 (1)
where 119870119894 is the sorption coefficient and 119863119894 is the diffusioncoefficientThe unit of permeability is Barrer that equals 10minus10(cm3cmsdotssdotcmHg) Experimentally the permeability can becalculated based on the flux [22]
119875 = 119869Δ119897
Δ119875 (2)
where 119869 is the flux (volume flow rate per unit area) Δ119897 is themembrane thickness andΔ119875 is the pressure difference across
the membrane On the other hand selectivity (120572119894119895) refers topermeability ratio of two gases
120572119894119895 =119875119894119875119895 (3)
The polymers are classified based on the structure to rubberyand glassy Rubbery polymers have the ability to return totheir original shape once stretched while glassy ones do not[23] Furthermore rubbery polymers tend to have higherpermeation but lower selectivity and this is because thetransport mechanism is controlled by absorption rather thandiffusion [24] Conversely glassy membranes have higherselectivity but low permeation because they are diffusionlimited This indicates that there is a trade-off between per-meability and selectivity and it is difficult to have a polymerhaving both characteristics In the following section uses ofmembranes for hydrogen sulfide separation carbon dioxiderecovery hydrogen purification air separation gas dehydra-tion organic vapors recovery and liquefied petroleum gas arediscussed in detail
3 Removal of Hydrogen Sulfide
Hydrogen sulfide is well known for its rotten-egg smell evenin low concertation of parts per billion (ppb) [28] The gas isemitted naturally from volcanoes and can be formed duringthe decomposition of organic matters [29] The gas is alsofound in natural gas and it is called sour gas if hydrogensulfide concertation is above 4 ppm [30] Because the gas iscorrosive and can cause damage to pipelines the sale gasshould not have more than 4 ppm of hydrogen sulfide and2mol of carbon dioxide [31] Hydrogen sulfide is a man-made gas too and dehydrosulfurization process (to removesulfur compounds from fuel) is considered as themain source[32]
31 Current Technologies There are threemethods for hydro-gen sulfide removal (1) physicalchemical absorption (2)adsorption and (3) membranes Chemical absorption byamine scrubbing is the dominant process for hydrogen sulfideseparation from natural gas [33] The process can removecarbon dioxide as well and the treated stream can have lowerthan 4 ppm of hydrogen sulfide The technology is based onthe absorption of hydrogen sulfide and then the reaction withamine by [34]
2RNH2 +H2Slarrrarr (RNH3)2 S (4)
(RNH3)2 S +H2Slarrrarr 2RNH3HS (5)
The solvent (mainlymonoethanolamineMEA) can be regen-erated by increasing the temperature or reducing the pres-sure In spite of the high efficiency of amine scrubbing thereare some drawbacks which are (1) high capital investment(2) massive energy required to regenerate the solvent (3)oxidation of amines which can cause foaming or floodingand (4) requirement of special alloys to withstand the solventcorrosivity [35ndash39]
International Journal of Polymer Science 3
Physical absorption by methanol is another way to rem-ove hydrogen sulfide from natural gas The process is calledRectisol (licensed by Linde Group and Air Liquide) and itcan remove carbon dioxide carbonyl sulfide and mercap-tans [40] At lower temperature the absorption capacity ofmethanol increases and that is why the process operates atminus30 to minus70∘C [41] It should be mentioned that methanolcan be replaced with other solvents like polyethylene glycol(Selexol process) or potassium carbonate but methanolhas better absorption capacity and higher regeneration rate[35 37 42 43] Compared to amine scrubber methanolabsorption has better removal efficiency but at the expenseof capital and operating costs [39]
Adsorption by carbon molecular sieve (CMS) is anothertechnique to separate hydrogen sulfide from methane Theconcept is based on adsorption of hydrogen sulfide on thecarbon surface at high pressure [44] Activated carbon haslarge surface area with high porosity and the capacity canreach 150mg of hydrogen sulfide to one gram of carbon[45]The desorption (regeneration) step can be performed byreducing the pressure or increasing the temperature to 288ndash316∘C [46] Unfortunately CMS cannot be used to removehigh content of hydrogen sulfide of more than 15mol dueto the lower adsorption capacity compared to amine scrubber[47] Furthermore carbon suffers from lowmechanical prop-erties making it unstable at high content of hydrogen sulfide[48]
The membrane technology can provide an alternativesolution for removal of hydrogen sulfide Unlike aminescrubbing or methanol absorption the membrane does notrequire a solvent to operate and this will cut down the costof purchasing and disposing of the solvent The membranehas also an advantage over CMS as it can operate withfeeds containing up to 16mol of hydrogen sulfide [31] Inthe following section performances of different membranematerials are reviewed for removal of hydrogen sulfide fromnatural gas
32 Membrane Materials Cellulose acetate is widely usedfor hydrogen sulfide removal from natural gas [49] Thismaterial is extracted from wood pulp and it has a hydrogensulfide permeability of 213 Barrer with hydrogen sulfide tomethane selectivity (120572H2SCH4) of 194 [50] The material wastested with natural gas containing heavy hydrocarbons andunexpectedly the selectivity dropped significantly due to thepenetration of sorption sites [50 51]
Polydimethylsiloxane (PDMS) gives a superior hydrogensulfide permeability of 2750 Barrer and this high permeabil-ity is related to the rubbery structure but at the expense ofselectivity of 098 [17] To enhance the membrane durabilityunder the harsh environment of hydrogen sulfide cross-linking was introduced [52] It helps in reducing the poly-meric chain mobility and this increases the glass transitiontemperature As a result resistance to plasticization andaging is improved [17] In addition cross-linking generallyaffects the segmental mobility of the polymer making thediffusion process rely more on the size and shape of themolecule to be separated and this improves the selectivity butreduces permeability [53] In 1997 Chatterjee et al developed
a copolymer consisting of ether urethane and urea and itwas prepared by the two-step polycondensation techniqueIn the first step methylene bis-(4-phenyl isocyanate) (MDI)is added to polyethylene glycol (PEG) with the use ofdimethyl sulfoxide (DMSO) as a solvent In the secondstep a chain extender (12-diaminoethane) was added tothe solution to form poly(ether-urethane-urea) (PUU) [50]Unlike membranes made of single polymer PUU consists oftwo segments soft and hard The hard segment has a glassystate and acts as a filler while the soft segment is rubberygiving the membrane elasticity and flexibility [54] PUU wastested for hydrogen sulfide separation frommethane and thepermeability was 199 Barrer with outstanding selectivity of 74[55]
Pebax is another copolymer made of polyether and poly-amide The term ldquoPebaxrdquo stands for polyether-block-amideand it was manufactured by Arkema [56] There are manygrades of Pebax and each grade depends on the concentrationof polyether and polyamide For example the popular Pebax1074 is made from 73wt polyether and 27wt polyamide[57] Hydrogen sulfide permeability of this material reached888 Barrer with selectivity of 21 [50] Permeability andselectivity of various membrane materials is given in Table 2The choice of material depends strongly on the compositionof the feed gas and whether permeability or selectivity is thefirst priority
33 Case Studies and Economical Evaluation MembraneTechnology and Research (MTR) is one of the companiesfor manufacturing gas-separation membranes SourSep (byMTR) is a membrane system to convert sour gas to sweetgas by the removal of hydrogen sulfide and it is expected tobe based on Pebax The unit was installed in an oil well in aremote area to treat wellhead gas so it can be used as a fuel[26] Indeed the system reduced hydrogen sulfide contentfrom 3400 ppm to less than 100 ppm The feed pressure wasat 51 bar and volume flow rate was 2001Nm3h Compared toamine scrubber themembrane system achieved lower capitaland operating costs The capital cost covers the membranematerial frame heat exchanger and vacuum pump whileoperating cost refers to energy used by compressors andpumps [17] FuelSep is another systemdeveloped byMTRanddesigned tomeet the quality of fuel gas by removing hydrogensulfide and other impurities such as carbon dioxide nitrogenand heavy hydrocarbons [2]
Universal Oil Products (UOP) Separex membrane isbased on cellulose acetate and designed to treat gases con-taining hydrogen sulfide up to 20mol [63] The system wascommercialized for nearly 30 years The system was installedin an off-shore gas reservoir containing 15mol of hydrogensulfide The feed volume was 588586Nm3h of gas at 92barThemembrane was capable of reducing hydrogen sulfidecontent to 70 ppm in the treated gas
An economical study was conducted by Bhide and Sternfor natural gas treatment using membranes and aminescrubbing [64] The membranes were based on celluloseacetate and content of hydrogen sulfide varied from 01to 1mol The feed also contained carbon dioxide of 5 to40mol Feed flow rate was 41201Nm3h at 54 bar The
4 International Journal of Polymer Science
Table 2 Permeability and selectivity of different polymeric membranes for removal of hydrogen sulfide from natural gas
processing cost (defined as the capital and operating costsover production volume) was calculated to achieve less than4 ppm of hydrogen sulfide and 2mol of carbon dioxide Itwas found that the processing cost in a membrane systemis a function of the concentration of hydrogen sulfide andcarbon dioxide the more the content the higher the costbut in amine scrubbing the processing cost was dependent oncarbon dioxide content only For a stream containing 1molhydrogen sulfide and 30mol carbon dioxide the processingcost for a membrane system was 487 times 10minus7 $(Nm3h) com-pared to 634 times 10minus7 $(Nm3h) for amine absorptionTherefore the use of membrane resulted in 23 reductionin processing cost However if the feed was changed to21mol carbon dioxide and 5000 ppm hydrogen sulfideboth systems had a processing cost of 487 times 10minus7 $(Nm3h)Amine scrubbing showed lower processing cost of 199 times10minus7 $(m3h) if the feed contained 5 carbon dioxide and1000 ppm hydrogen sulfide while the membrane gives 354 times10minus7 $(Nm3h)
4 Carbon Dioxide Capture
The atmosphere consists before of 315 ppm carbon dioxide(1955 reading) but because of the transportation and indus-trial activities the content is increased to 390 ppm causingglobal warming and increase in the climate temperature [65]The petroleum industry accounts for 8 of carbon dioxideemission and in order to reduce the impact carbon capturefrom flue gases is necessary [66]
In the refinery separation of carbon dioxide is requiredin the following processes natural gas treatment syngas pro-duction (hydrogen and carbon monoxide) and combustionToday wells are injected with a high-pressure carbon dioxidestream to enhance the oil recovery and this results in pro-duction of natural gas with high amounts of carbon dioxide[67] Removal of this carbon dioxide is essential because thegas is corrosive and can damage pipelines [68]Themaximum
content of carbon dioxide in commercial natural gas shouldnot exceed 2mol [31] Furthermore the flue gases of mostcombustion processes (furnaces) have amounts of carbondioxide and nitrogen Carbon dioxide capture is necessarilybefore releasing this gas to the atmosphere [69]
41 Current Technologies Most of the techniques for hydro-gen sulfide removal work as well for carbon dioxide becauseboth gases are polar The dominant method for carbon diox-ide removal from natural gas is still amine scrubbing [34]The process can remove bulk quantities of carbon dioxideand the final stream can have as low as 50 ppm of carbondioxide [39] Physical absorption by water polyethyleneglycol methanol and potassium carbonate is possible toseparate carbon dioxide In water absorption the gas entersa packed tower where carbon dioxide dissolves in waterand the concentrated stream is stripped by air to generatecarbon dioxide back and water is recycled The process iscost effective because water is readily available however therecirculated water can cause fouling therefore special pipingis needed [70] Polyethylene glycol (PEG) on the other handhas better selectivity compared to water and is considered as anoncorrosive solvent [43] The drawback of using PEG is thelow regeneration rate [43]
Hot potassium carbonate is efficient for removing largeamounts of carbon dioxide The process can also removesmall amounts of hydrogen sulfide The mechanism is basedon the reaction of carbon dioxide with potassium carbonatesolution [35]
K2CO3 + CO2 +H2Olarrrarr 2KHCO3 (6)
The carbon dioxide-enriched stream enters an absorberwhere it flows in a counter-current with a hot potassiumcarbonate solution at 110∘C [71] The solution is then sent toa flash drum where most of the acid gas will be removeddue to the reduction of the pressure To regenerate thesolvent it is sent to a stripper that operates at 120∘C and
International Journal of Polymer Science 5
Table 3 Current technologies for carbon dioxide separation
(i) Achieves gt99 of CO2 capture(ii) Produces liquefied CO2 for easier storage
(i) Economical only if the feed contains 50ndash70 CO2(ii) Higher pressure is required to avoid CO2 sublimation
Membranes(i) Requires minimum supervision(ii) Can remove H2S and H2O as well(iii) Long-operating life (gt5 years)
(i) High capital cost(ii) Pretreatment is required to remove particulates and some inhibitors
atmospheric pressure Unfortunately potassium carbonatehas lower sorption properties compared to amine and it ishighly corrosive [37 42]
Methanol can also be used for physical absorption ofcarbon dioxide and it has the highest selectivity compared toother solvents [39] The solvent can be regenerated by eitherreducing the pressure or increasing the temperature [40]Thefinal stream can have very low amounts of carbon dioxideof 10 ppm which is more efficient than amine scrubbingThe only disadvantage of this process is the high capitalinvestment [39]
Pressure swing adsorption (PSA) is another techniquefor carbon dioxide separation Unlike previous methodsPSA does not require a solvent The gas passes at a highpressure through a bed of activated carbon (also known ascarbon molecular sieve) and due to the difference in polarityadsorption of carbon dioxide will take place [72] The bedcan be regenerated by reducing the pressure to vacuumThe technique has an excellent separation performance andthe gas can have more than 90 methane purity and it isexpected to run for three years [73] Other PSA materialsare zeolite and alumina Disadvantages of this system arethe extensive energy for pressure cycle and low adsorptioncapacity compared to amine scrubbing [74]
Cryogenic distillation at very low temperature of minus84∘Cis efficient for carbon dioxide removal Because of the lowtriple point of carbon dioxide of minus57∘C at atmosphericpressure carbon dioxide will not have a liquid state and willsolidify directly [75] Therefore the distillation should takeplace at a pressure above 5 bar to overcome the triple pointlimitation otherwise carbon dioxide will cause blockageThe technology is used to liquify and produce high qualitystreams of carbon dioxide For the process to be economicalthe feed should contain 50 to 70 carbon dioxide and this isbecause of the high capital and operating costs of cryogenicdistillation [73] Unfortunately most of the refinery streamsdo not have that concentration of carbon dioxide [72]
In comparison with the above-mentioned the mem-branes have a unique feature as they can remove carbondioxide along hydrogen sulfide and water with one step [7677] In addition to low operating energy the membrane has along life and it can be operated continuously for at least 5 years
[78] However the operating life is greatly affected if partic-ulates were presented in the feed therefore pretreatment isneeded Table 3 shows the advantages and disadvantages ofdifferent methods for carbon dioxide capture
42 MembraneMaterials Removal of carbon dioxide startedwhen Robb studied in 1968 the diffusion of gases in PDMSmembrane [61] The work was expanded in 1989 when Sterndetermined the permeability coefficient of gases at highertemperature [17] CO2-permeable membranes are similar tothose that permeate hydrogen sulfide but the permeabil-ity differs due to the difference in sorption and diffusioncoefficients between carbon dioxide and hydrogen sulfideThe state-of-the-art materials for carbon dioxide separationare cellulose acetate polyamide polyimide and Pebax Asshown inTable 4 cellulose acetate has the lowest permeabilityof 24 Barrer but yet the selectivity of carbon dioxide tomethane (120572CO2CH4) reached 25 [25 50] Unfortunately pre-sence of heavy hydrocarbons in the feed caused a sig-nificant drop in the selectivity therefore cellulose acetatewas not suitable for fuel gas separation [50] Polyimideson the other hand show better thermal and chemical sta-bilities compared to cellulose acetate [2] These polymersare made from diacid with diamine in amic acid inter-mediate [79] Matrimid 5218 is a polyimide containingphenylindane group and it gives carbon dioxide permeabil-ity of 85 Barrer [1 80] This polymer shows outstandingselectivity of 28 and 367 for carbon dioxide to methane(120572CO2CH4) and carbon dioxide to nitrogen (120572CO2N2) respec-tively [81 82] Carbon dioxide permeability of polyimidecan be further enhanced by the introduction of fluo-ride Fluorinated polyimides are made using 22-bis(34-di-carboxyphenyl)hexafluoropropanedianhydride (6FDA) andthe permeability can be boosted to 456 Barrer [83 84]Copolymers like PUUand Pebax show also high permeabilityof 145 and 212 Barrer respectively [85 86] The rubberypolymer PDMS has an excellent permeability of 4000 Barrerbut the lowest carbon dioxide selectivity of 26 as given inTable 4
43 Commercial Units and Economical Evaluation Thelargest CO2-removal unit is manufactured by Cynara
6 International Journal of Polymer Science
Table 4 Permeability and selectivity of different polymers for carbon dioxide removal
(NATCO Group) for natural gas sweeting in an off-shorearea in Thailand The hollow fiber membrane is based oncellulose triacetate and capable of handling 830000Nm3h[25] Another system was installed to treat 120000Nm3h ofgas and it reduced carbon dioxide content from 80 to lessthan 10 [77 93]
Polaris membrane (made by MTR) was installed aftermethane-reforming unit and it successfully increased carbondioxide concentration from 20mol in the tail gas to morethan 90mol [26] The stream was used afterwards for wellinjection to enhance oil recovery Polaris membrane can alsotreat flue gases with excellent selectivity (120572CO2N2) of 50 [94]
UOP membranes are based on cellulose acetate and wereinstalled in Pakistan in 1995The systemworked continuouslyfor 12 years to cut down carbon dioxide concentration from65 to 2mol [63] The system was designed to process311950Nm3h of gas at 58 bar
UBE on the other hand developed a robust membrane forbetter stability under feed impurities The system is based onpolyimide membrane and it can work without any drop inperformance under the presence of 3mol hydrogen sulfidefull water saturation and heavy hydrogen carbons of C5+[95]
An economical study was done by Peters et al to comparethe membrane system with amine scrubbing for natural gaspurification [96] The feed gas contained 95mol CO220 ppm H2S 10 ppm H2O and 724mol CH4 and theremaining for C2 to C6 The operating conditions were 60∘Cand 90 bar Results show that both technologies achievedthe sale gas specification of 4 ppm H2S and 2mol CO2however the treated gas by amine has better carbon dioxidepurity compared to themembrane but this was at the expenseof the capital investment It was concluded that themembranetechnology was still a better choice due to the environmentalissue related to solvent disposal
Another economical evaluation was performed by He etal and it confirmed that the membrane can replace aminescrubbing for natural gas treatment containing 10mol
carbon dioxide and lower [97] Natural gas processing cost bythe membrane system was 000573 $Nm3 which was 104less than amine scrubbing
5 Hydrogen Recovery
Hydrogen is a key element for many processes in the refinerysuch as hydrocracking and hydrotreating In hydrocrackinghydrogen is used to convert large hydrocarbons into smallerones in presence of a catalyst while in hydrotreating hydro-gen is used to remove sulfur compounds from fuels in theform of hydrogen sulfide [98] Furthermore hydrogen is afeedstock for many industries like ammonia synthesis andmethanol production [99]
Hydrogen is produced in the refinery by steam-methanereforming (SMR) where methane reacts with water to pro-duce hydrogen and carbon monoxide The produced gas iscalled syngas and hydrogen yield can be further increasedby the reaction of carbon monoxide with water to formhydrogen and carbon dioxide [100]
In petroleum industry hydrogen separation can be prac-ticed in the following processes (1) to recover some hydrogenduring natural gas production (2) to adjust hydrogen-to-carbon monoxide ratio (H2CO) in syngas (3) to recyclepart of hydrogen from hydrocracker and hydrotreatment tailgases (4) to separate hydrogen from nitrogen in ammoniaplant and (5) to purify hydrogen so it can be used as afeedstock for other industries [102ndash104] Content of hydrogenin refinery off-gases is given in Table 5
51 Current Technologies Mainly there are three methodsto separate hydrogen from gas mixtures (1) cryogenic dis-tillation (2) PSA and (3) membrane system The selectionof technology depends on feed composition product purityproduct flow rate reliability turndown and last but not leastcapital and operating costs Comparison between the threetechnologies is given in Table 6 As indicated the membranehas a better capability to treat a wider range of hydrogen from
International Journal of Polymer Science 7
Table 5 Hydrogen composition in refinery off-gases [101]
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
Physical absorption by methanol is another way to rem-ove hydrogen sulfide from natural gas The process is calledRectisol (licensed by Linde Group and Air Liquide) and itcan remove carbon dioxide carbonyl sulfide and mercap-tans [40] At lower temperature the absorption capacity ofmethanol increases and that is why the process operates atminus30 to minus70∘C [41] It should be mentioned that methanolcan be replaced with other solvents like polyethylene glycol(Selexol process) or potassium carbonate but methanolhas better absorption capacity and higher regeneration rate[35 37 42 43] Compared to amine scrubber methanolabsorption has better removal efficiency but at the expenseof capital and operating costs [39]
Adsorption by carbon molecular sieve (CMS) is anothertechnique to separate hydrogen sulfide from methane Theconcept is based on adsorption of hydrogen sulfide on thecarbon surface at high pressure [44] Activated carbon haslarge surface area with high porosity and the capacity canreach 150mg of hydrogen sulfide to one gram of carbon[45]The desorption (regeneration) step can be performed byreducing the pressure or increasing the temperature to 288ndash316∘C [46] Unfortunately CMS cannot be used to removehigh content of hydrogen sulfide of more than 15mol dueto the lower adsorption capacity compared to amine scrubber[47] Furthermore carbon suffers from lowmechanical prop-erties making it unstable at high content of hydrogen sulfide[48]
The membrane technology can provide an alternativesolution for removal of hydrogen sulfide Unlike aminescrubbing or methanol absorption the membrane does notrequire a solvent to operate and this will cut down the costof purchasing and disposing of the solvent The membranehas also an advantage over CMS as it can operate withfeeds containing up to 16mol of hydrogen sulfide [31] Inthe following section performances of different membranematerials are reviewed for removal of hydrogen sulfide fromnatural gas
32 Membrane Materials Cellulose acetate is widely usedfor hydrogen sulfide removal from natural gas [49] Thismaterial is extracted from wood pulp and it has a hydrogensulfide permeability of 213 Barrer with hydrogen sulfide tomethane selectivity (120572H2SCH4) of 194 [50] The material wastested with natural gas containing heavy hydrocarbons andunexpectedly the selectivity dropped significantly due to thepenetration of sorption sites [50 51]
Polydimethylsiloxane (PDMS) gives a superior hydrogensulfide permeability of 2750 Barrer and this high permeabil-ity is related to the rubbery structure but at the expense ofselectivity of 098 [17] To enhance the membrane durabilityunder the harsh environment of hydrogen sulfide cross-linking was introduced [52] It helps in reducing the poly-meric chain mobility and this increases the glass transitiontemperature As a result resistance to plasticization andaging is improved [17] In addition cross-linking generallyaffects the segmental mobility of the polymer making thediffusion process rely more on the size and shape of themolecule to be separated and this improves the selectivity butreduces permeability [53] In 1997 Chatterjee et al developed
a copolymer consisting of ether urethane and urea and itwas prepared by the two-step polycondensation techniqueIn the first step methylene bis-(4-phenyl isocyanate) (MDI)is added to polyethylene glycol (PEG) with the use ofdimethyl sulfoxide (DMSO) as a solvent In the secondstep a chain extender (12-diaminoethane) was added tothe solution to form poly(ether-urethane-urea) (PUU) [50]Unlike membranes made of single polymer PUU consists oftwo segments soft and hard The hard segment has a glassystate and acts as a filler while the soft segment is rubberygiving the membrane elasticity and flexibility [54] PUU wastested for hydrogen sulfide separation frommethane and thepermeability was 199 Barrer with outstanding selectivity of 74[55]
Pebax is another copolymer made of polyether and poly-amide The term ldquoPebaxrdquo stands for polyether-block-amideand it was manufactured by Arkema [56] There are manygrades of Pebax and each grade depends on the concentrationof polyether and polyamide For example the popular Pebax1074 is made from 73wt polyether and 27wt polyamide[57] Hydrogen sulfide permeability of this material reached888 Barrer with selectivity of 21 [50] Permeability andselectivity of various membrane materials is given in Table 2The choice of material depends strongly on the compositionof the feed gas and whether permeability or selectivity is thefirst priority
33 Case Studies and Economical Evaluation MembraneTechnology and Research (MTR) is one of the companiesfor manufacturing gas-separation membranes SourSep (byMTR) is a membrane system to convert sour gas to sweetgas by the removal of hydrogen sulfide and it is expected tobe based on Pebax The unit was installed in an oil well in aremote area to treat wellhead gas so it can be used as a fuel[26] Indeed the system reduced hydrogen sulfide contentfrom 3400 ppm to less than 100 ppm The feed pressure wasat 51 bar and volume flow rate was 2001Nm3h Compared toamine scrubber themembrane system achieved lower capitaland operating costs The capital cost covers the membranematerial frame heat exchanger and vacuum pump whileoperating cost refers to energy used by compressors andpumps [17] FuelSep is another systemdeveloped byMTRanddesigned tomeet the quality of fuel gas by removing hydrogensulfide and other impurities such as carbon dioxide nitrogenand heavy hydrocarbons [2]
Universal Oil Products (UOP) Separex membrane isbased on cellulose acetate and designed to treat gases con-taining hydrogen sulfide up to 20mol [63] The system wascommercialized for nearly 30 years The system was installedin an off-shore gas reservoir containing 15mol of hydrogensulfide The feed volume was 588586Nm3h of gas at 92barThemembrane was capable of reducing hydrogen sulfidecontent to 70 ppm in the treated gas
An economical study was conducted by Bhide and Sternfor natural gas treatment using membranes and aminescrubbing [64] The membranes were based on celluloseacetate and content of hydrogen sulfide varied from 01to 1mol The feed also contained carbon dioxide of 5 to40mol Feed flow rate was 41201Nm3h at 54 bar The
4 International Journal of Polymer Science
Table 2 Permeability and selectivity of different polymeric membranes for removal of hydrogen sulfide from natural gas
processing cost (defined as the capital and operating costsover production volume) was calculated to achieve less than4 ppm of hydrogen sulfide and 2mol of carbon dioxide Itwas found that the processing cost in a membrane systemis a function of the concentration of hydrogen sulfide andcarbon dioxide the more the content the higher the costbut in amine scrubbing the processing cost was dependent oncarbon dioxide content only For a stream containing 1molhydrogen sulfide and 30mol carbon dioxide the processingcost for a membrane system was 487 times 10minus7 $(Nm3h) com-pared to 634 times 10minus7 $(Nm3h) for amine absorptionTherefore the use of membrane resulted in 23 reductionin processing cost However if the feed was changed to21mol carbon dioxide and 5000 ppm hydrogen sulfideboth systems had a processing cost of 487 times 10minus7 $(Nm3h)Amine scrubbing showed lower processing cost of 199 times10minus7 $(m3h) if the feed contained 5 carbon dioxide and1000 ppm hydrogen sulfide while the membrane gives 354 times10minus7 $(Nm3h)
4 Carbon Dioxide Capture
The atmosphere consists before of 315 ppm carbon dioxide(1955 reading) but because of the transportation and indus-trial activities the content is increased to 390 ppm causingglobal warming and increase in the climate temperature [65]The petroleum industry accounts for 8 of carbon dioxideemission and in order to reduce the impact carbon capturefrom flue gases is necessary [66]
In the refinery separation of carbon dioxide is requiredin the following processes natural gas treatment syngas pro-duction (hydrogen and carbon monoxide) and combustionToday wells are injected with a high-pressure carbon dioxidestream to enhance the oil recovery and this results in pro-duction of natural gas with high amounts of carbon dioxide[67] Removal of this carbon dioxide is essential because thegas is corrosive and can damage pipelines [68]Themaximum
content of carbon dioxide in commercial natural gas shouldnot exceed 2mol [31] Furthermore the flue gases of mostcombustion processes (furnaces) have amounts of carbondioxide and nitrogen Carbon dioxide capture is necessarilybefore releasing this gas to the atmosphere [69]
41 Current Technologies Most of the techniques for hydro-gen sulfide removal work as well for carbon dioxide becauseboth gases are polar The dominant method for carbon diox-ide removal from natural gas is still amine scrubbing [34]The process can remove bulk quantities of carbon dioxideand the final stream can have as low as 50 ppm of carbondioxide [39] Physical absorption by water polyethyleneglycol methanol and potassium carbonate is possible toseparate carbon dioxide In water absorption the gas entersa packed tower where carbon dioxide dissolves in waterand the concentrated stream is stripped by air to generatecarbon dioxide back and water is recycled The process iscost effective because water is readily available however therecirculated water can cause fouling therefore special pipingis needed [70] Polyethylene glycol (PEG) on the other handhas better selectivity compared to water and is considered as anoncorrosive solvent [43] The drawback of using PEG is thelow regeneration rate [43]
Hot potassium carbonate is efficient for removing largeamounts of carbon dioxide The process can also removesmall amounts of hydrogen sulfide The mechanism is basedon the reaction of carbon dioxide with potassium carbonatesolution [35]
K2CO3 + CO2 +H2Olarrrarr 2KHCO3 (6)
The carbon dioxide-enriched stream enters an absorberwhere it flows in a counter-current with a hot potassiumcarbonate solution at 110∘C [71] The solution is then sent toa flash drum where most of the acid gas will be removeddue to the reduction of the pressure To regenerate thesolvent it is sent to a stripper that operates at 120∘C and
International Journal of Polymer Science 5
Table 3 Current technologies for carbon dioxide separation
(i) Achieves gt99 of CO2 capture(ii) Produces liquefied CO2 for easier storage
(i) Economical only if the feed contains 50ndash70 CO2(ii) Higher pressure is required to avoid CO2 sublimation
Membranes(i) Requires minimum supervision(ii) Can remove H2S and H2O as well(iii) Long-operating life (gt5 years)
(i) High capital cost(ii) Pretreatment is required to remove particulates and some inhibitors
atmospheric pressure Unfortunately potassium carbonatehas lower sorption properties compared to amine and it ishighly corrosive [37 42]
Methanol can also be used for physical absorption ofcarbon dioxide and it has the highest selectivity compared toother solvents [39] The solvent can be regenerated by eitherreducing the pressure or increasing the temperature [40]Thefinal stream can have very low amounts of carbon dioxideof 10 ppm which is more efficient than amine scrubbingThe only disadvantage of this process is the high capitalinvestment [39]
Pressure swing adsorption (PSA) is another techniquefor carbon dioxide separation Unlike previous methodsPSA does not require a solvent The gas passes at a highpressure through a bed of activated carbon (also known ascarbon molecular sieve) and due to the difference in polarityadsorption of carbon dioxide will take place [72] The bedcan be regenerated by reducing the pressure to vacuumThe technique has an excellent separation performance andthe gas can have more than 90 methane purity and it isexpected to run for three years [73] Other PSA materialsare zeolite and alumina Disadvantages of this system arethe extensive energy for pressure cycle and low adsorptioncapacity compared to amine scrubbing [74]
Cryogenic distillation at very low temperature of minus84∘Cis efficient for carbon dioxide removal Because of the lowtriple point of carbon dioxide of minus57∘C at atmosphericpressure carbon dioxide will not have a liquid state and willsolidify directly [75] Therefore the distillation should takeplace at a pressure above 5 bar to overcome the triple pointlimitation otherwise carbon dioxide will cause blockageThe technology is used to liquify and produce high qualitystreams of carbon dioxide For the process to be economicalthe feed should contain 50 to 70 carbon dioxide and this isbecause of the high capital and operating costs of cryogenicdistillation [73] Unfortunately most of the refinery streamsdo not have that concentration of carbon dioxide [72]
In comparison with the above-mentioned the mem-branes have a unique feature as they can remove carbondioxide along hydrogen sulfide and water with one step [7677] In addition to low operating energy the membrane has along life and it can be operated continuously for at least 5 years
[78] However the operating life is greatly affected if partic-ulates were presented in the feed therefore pretreatment isneeded Table 3 shows the advantages and disadvantages ofdifferent methods for carbon dioxide capture
42 MembraneMaterials Removal of carbon dioxide startedwhen Robb studied in 1968 the diffusion of gases in PDMSmembrane [61] The work was expanded in 1989 when Sterndetermined the permeability coefficient of gases at highertemperature [17] CO2-permeable membranes are similar tothose that permeate hydrogen sulfide but the permeabil-ity differs due to the difference in sorption and diffusioncoefficients between carbon dioxide and hydrogen sulfideThe state-of-the-art materials for carbon dioxide separationare cellulose acetate polyamide polyimide and Pebax Asshown inTable 4 cellulose acetate has the lowest permeabilityof 24 Barrer but yet the selectivity of carbon dioxide tomethane (120572CO2CH4) reached 25 [25 50] Unfortunately pre-sence of heavy hydrocarbons in the feed caused a sig-nificant drop in the selectivity therefore cellulose acetatewas not suitable for fuel gas separation [50] Polyimideson the other hand show better thermal and chemical sta-bilities compared to cellulose acetate [2] These polymersare made from diacid with diamine in amic acid inter-mediate [79] Matrimid 5218 is a polyimide containingphenylindane group and it gives carbon dioxide permeabil-ity of 85 Barrer [1 80] This polymer shows outstandingselectivity of 28 and 367 for carbon dioxide to methane(120572CO2CH4) and carbon dioxide to nitrogen (120572CO2N2) respec-tively [81 82] Carbon dioxide permeability of polyimidecan be further enhanced by the introduction of fluo-ride Fluorinated polyimides are made using 22-bis(34-di-carboxyphenyl)hexafluoropropanedianhydride (6FDA) andthe permeability can be boosted to 456 Barrer [83 84]Copolymers like PUUand Pebax show also high permeabilityof 145 and 212 Barrer respectively [85 86] The rubberypolymer PDMS has an excellent permeability of 4000 Barrerbut the lowest carbon dioxide selectivity of 26 as given inTable 4
43 Commercial Units and Economical Evaluation Thelargest CO2-removal unit is manufactured by Cynara
6 International Journal of Polymer Science
Table 4 Permeability and selectivity of different polymers for carbon dioxide removal
(NATCO Group) for natural gas sweeting in an off-shorearea in Thailand The hollow fiber membrane is based oncellulose triacetate and capable of handling 830000Nm3h[25] Another system was installed to treat 120000Nm3h ofgas and it reduced carbon dioxide content from 80 to lessthan 10 [77 93]
Polaris membrane (made by MTR) was installed aftermethane-reforming unit and it successfully increased carbondioxide concentration from 20mol in the tail gas to morethan 90mol [26] The stream was used afterwards for wellinjection to enhance oil recovery Polaris membrane can alsotreat flue gases with excellent selectivity (120572CO2N2) of 50 [94]
UOP membranes are based on cellulose acetate and wereinstalled in Pakistan in 1995The systemworked continuouslyfor 12 years to cut down carbon dioxide concentration from65 to 2mol [63] The system was designed to process311950Nm3h of gas at 58 bar
UBE on the other hand developed a robust membrane forbetter stability under feed impurities The system is based onpolyimide membrane and it can work without any drop inperformance under the presence of 3mol hydrogen sulfidefull water saturation and heavy hydrogen carbons of C5+[95]
An economical study was done by Peters et al to comparethe membrane system with amine scrubbing for natural gaspurification [96] The feed gas contained 95mol CO220 ppm H2S 10 ppm H2O and 724mol CH4 and theremaining for C2 to C6 The operating conditions were 60∘Cand 90 bar Results show that both technologies achievedthe sale gas specification of 4 ppm H2S and 2mol CO2however the treated gas by amine has better carbon dioxidepurity compared to themembrane but this was at the expenseof the capital investment It was concluded that themembranetechnology was still a better choice due to the environmentalissue related to solvent disposal
Another economical evaluation was performed by He etal and it confirmed that the membrane can replace aminescrubbing for natural gas treatment containing 10mol
carbon dioxide and lower [97] Natural gas processing cost bythe membrane system was 000573 $Nm3 which was 104less than amine scrubbing
5 Hydrogen Recovery
Hydrogen is a key element for many processes in the refinerysuch as hydrocracking and hydrotreating In hydrocrackinghydrogen is used to convert large hydrocarbons into smallerones in presence of a catalyst while in hydrotreating hydro-gen is used to remove sulfur compounds from fuels in theform of hydrogen sulfide [98] Furthermore hydrogen is afeedstock for many industries like ammonia synthesis andmethanol production [99]
Hydrogen is produced in the refinery by steam-methanereforming (SMR) where methane reacts with water to pro-duce hydrogen and carbon monoxide The produced gas iscalled syngas and hydrogen yield can be further increasedby the reaction of carbon monoxide with water to formhydrogen and carbon dioxide [100]
In petroleum industry hydrogen separation can be prac-ticed in the following processes (1) to recover some hydrogenduring natural gas production (2) to adjust hydrogen-to-carbon monoxide ratio (H2CO) in syngas (3) to recyclepart of hydrogen from hydrocracker and hydrotreatment tailgases (4) to separate hydrogen from nitrogen in ammoniaplant and (5) to purify hydrogen so it can be used as afeedstock for other industries [102ndash104] Content of hydrogenin refinery off-gases is given in Table 5
51 Current Technologies Mainly there are three methodsto separate hydrogen from gas mixtures (1) cryogenic dis-tillation (2) PSA and (3) membrane system The selectionof technology depends on feed composition product purityproduct flow rate reliability turndown and last but not leastcapital and operating costs Comparison between the threetechnologies is given in Table 6 As indicated the membranehas a better capability to treat a wider range of hydrogen from
International Journal of Polymer Science 7
Table 5 Hydrogen composition in refinery off-gases [101]
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
processing cost (defined as the capital and operating costsover production volume) was calculated to achieve less than4 ppm of hydrogen sulfide and 2mol of carbon dioxide Itwas found that the processing cost in a membrane systemis a function of the concentration of hydrogen sulfide andcarbon dioxide the more the content the higher the costbut in amine scrubbing the processing cost was dependent oncarbon dioxide content only For a stream containing 1molhydrogen sulfide and 30mol carbon dioxide the processingcost for a membrane system was 487 times 10minus7 $(Nm3h) com-pared to 634 times 10minus7 $(Nm3h) for amine absorptionTherefore the use of membrane resulted in 23 reductionin processing cost However if the feed was changed to21mol carbon dioxide and 5000 ppm hydrogen sulfideboth systems had a processing cost of 487 times 10minus7 $(Nm3h)Amine scrubbing showed lower processing cost of 199 times10minus7 $(m3h) if the feed contained 5 carbon dioxide and1000 ppm hydrogen sulfide while the membrane gives 354 times10minus7 $(Nm3h)
4 Carbon Dioxide Capture
The atmosphere consists before of 315 ppm carbon dioxide(1955 reading) but because of the transportation and indus-trial activities the content is increased to 390 ppm causingglobal warming and increase in the climate temperature [65]The petroleum industry accounts for 8 of carbon dioxideemission and in order to reduce the impact carbon capturefrom flue gases is necessary [66]
In the refinery separation of carbon dioxide is requiredin the following processes natural gas treatment syngas pro-duction (hydrogen and carbon monoxide) and combustionToday wells are injected with a high-pressure carbon dioxidestream to enhance the oil recovery and this results in pro-duction of natural gas with high amounts of carbon dioxide[67] Removal of this carbon dioxide is essential because thegas is corrosive and can damage pipelines [68]Themaximum
content of carbon dioxide in commercial natural gas shouldnot exceed 2mol [31] Furthermore the flue gases of mostcombustion processes (furnaces) have amounts of carbondioxide and nitrogen Carbon dioxide capture is necessarilybefore releasing this gas to the atmosphere [69]
41 Current Technologies Most of the techniques for hydro-gen sulfide removal work as well for carbon dioxide becauseboth gases are polar The dominant method for carbon diox-ide removal from natural gas is still amine scrubbing [34]The process can remove bulk quantities of carbon dioxideand the final stream can have as low as 50 ppm of carbondioxide [39] Physical absorption by water polyethyleneglycol methanol and potassium carbonate is possible toseparate carbon dioxide In water absorption the gas entersa packed tower where carbon dioxide dissolves in waterand the concentrated stream is stripped by air to generatecarbon dioxide back and water is recycled The process iscost effective because water is readily available however therecirculated water can cause fouling therefore special pipingis needed [70] Polyethylene glycol (PEG) on the other handhas better selectivity compared to water and is considered as anoncorrosive solvent [43] The drawback of using PEG is thelow regeneration rate [43]
Hot potassium carbonate is efficient for removing largeamounts of carbon dioxide The process can also removesmall amounts of hydrogen sulfide The mechanism is basedon the reaction of carbon dioxide with potassium carbonatesolution [35]
K2CO3 + CO2 +H2Olarrrarr 2KHCO3 (6)
The carbon dioxide-enriched stream enters an absorberwhere it flows in a counter-current with a hot potassiumcarbonate solution at 110∘C [71] The solution is then sent toa flash drum where most of the acid gas will be removeddue to the reduction of the pressure To regenerate thesolvent it is sent to a stripper that operates at 120∘C and
International Journal of Polymer Science 5
Table 3 Current technologies for carbon dioxide separation
(i) Achieves gt99 of CO2 capture(ii) Produces liquefied CO2 for easier storage
(i) Economical only if the feed contains 50ndash70 CO2(ii) Higher pressure is required to avoid CO2 sublimation
Membranes(i) Requires minimum supervision(ii) Can remove H2S and H2O as well(iii) Long-operating life (gt5 years)
(i) High capital cost(ii) Pretreatment is required to remove particulates and some inhibitors
atmospheric pressure Unfortunately potassium carbonatehas lower sorption properties compared to amine and it ishighly corrosive [37 42]
Methanol can also be used for physical absorption ofcarbon dioxide and it has the highest selectivity compared toother solvents [39] The solvent can be regenerated by eitherreducing the pressure or increasing the temperature [40]Thefinal stream can have very low amounts of carbon dioxideof 10 ppm which is more efficient than amine scrubbingThe only disadvantage of this process is the high capitalinvestment [39]
Pressure swing adsorption (PSA) is another techniquefor carbon dioxide separation Unlike previous methodsPSA does not require a solvent The gas passes at a highpressure through a bed of activated carbon (also known ascarbon molecular sieve) and due to the difference in polarityadsorption of carbon dioxide will take place [72] The bedcan be regenerated by reducing the pressure to vacuumThe technique has an excellent separation performance andthe gas can have more than 90 methane purity and it isexpected to run for three years [73] Other PSA materialsare zeolite and alumina Disadvantages of this system arethe extensive energy for pressure cycle and low adsorptioncapacity compared to amine scrubbing [74]
Cryogenic distillation at very low temperature of minus84∘Cis efficient for carbon dioxide removal Because of the lowtriple point of carbon dioxide of minus57∘C at atmosphericpressure carbon dioxide will not have a liquid state and willsolidify directly [75] Therefore the distillation should takeplace at a pressure above 5 bar to overcome the triple pointlimitation otherwise carbon dioxide will cause blockageThe technology is used to liquify and produce high qualitystreams of carbon dioxide For the process to be economicalthe feed should contain 50 to 70 carbon dioxide and this isbecause of the high capital and operating costs of cryogenicdistillation [73] Unfortunately most of the refinery streamsdo not have that concentration of carbon dioxide [72]
In comparison with the above-mentioned the mem-branes have a unique feature as they can remove carbondioxide along hydrogen sulfide and water with one step [7677] In addition to low operating energy the membrane has along life and it can be operated continuously for at least 5 years
[78] However the operating life is greatly affected if partic-ulates were presented in the feed therefore pretreatment isneeded Table 3 shows the advantages and disadvantages ofdifferent methods for carbon dioxide capture
42 MembraneMaterials Removal of carbon dioxide startedwhen Robb studied in 1968 the diffusion of gases in PDMSmembrane [61] The work was expanded in 1989 when Sterndetermined the permeability coefficient of gases at highertemperature [17] CO2-permeable membranes are similar tothose that permeate hydrogen sulfide but the permeabil-ity differs due to the difference in sorption and diffusioncoefficients between carbon dioxide and hydrogen sulfideThe state-of-the-art materials for carbon dioxide separationare cellulose acetate polyamide polyimide and Pebax Asshown inTable 4 cellulose acetate has the lowest permeabilityof 24 Barrer but yet the selectivity of carbon dioxide tomethane (120572CO2CH4) reached 25 [25 50] Unfortunately pre-sence of heavy hydrocarbons in the feed caused a sig-nificant drop in the selectivity therefore cellulose acetatewas not suitable for fuel gas separation [50] Polyimideson the other hand show better thermal and chemical sta-bilities compared to cellulose acetate [2] These polymersare made from diacid with diamine in amic acid inter-mediate [79] Matrimid 5218 is a polyimide containingphenylindane group and it gives carbon dioxide permeabil-ity of 85 Barrer [1 80] This polymer shows outstandingselectivity of 28 and 367 for carbon dioxide to methane(120572CO2CH4) and carbon dioxide to nitrogen (120572CO2N2) respec-tively [81 82] Carbon dioxide permeability of polyimidecan be further enhanced by the introduction of fluo-ride Fluorinated polyimides are made using 22-bis(34-di-carboxyphenyl)hexafluoropropanedianhydride (6FDA) andthe permeability can be boosted to 456 Barrer [83 84]Copolymers like PUUand Pebax show also high permeabilityof 145 and 212 Barrer respectively [85 86] The rubberypolymer PDMS has an excellent permeability of 4000 Barrerbut the lowest carbon dioxide selectivity of 26 as given inTable 4
43 Commercial Units and Economical Evaluation Thelargest CO2-removal unit is manufactured by Cynara
6 International Journal of Polymer Science
Table 4 Permeability and selectivity of different polymers for carbon dioxide removal
(NATCO Group) for natural gas sweeting in an off-shorearea in Thailand The hollow fiber membrane is based oncellulose triacetate and capable of handling 830000Nm3h[25] Another system was installed to treat 120000Nm3h ofgas and it reduced carbon dioxide content from 80 to lessthan 10 [77 93]
Polaris membrane (made by MTR) was installed aftermethane-reforming unit and it successfully increased carbondioxide concentration from 20mol in the tail gas to morethan 90mol [26] The stream was used afterwards for wellinjection to enhance oil recovery Polaris membrane can alsotreat flue gases with excellent selectivity (120572CO2N2) of 50 [94]
UOP membranes are based on cellulose acetate and wereinstalled in Pakistan in 1995The systemworked continuouslyfor 12 years to cut down carbon dioxide concentration from65 to 2mol [63] The system was designed to process311950Nm3h of gas at 58 bar
UBE on the other hand developed a robust membrane forbetter stability under feed impurities The system is based onpolyimide membrane and it can work without any drop inperformance under the presence of 3mol hydrogen sulfidefull water saturation and heavy hydrogen carbons of C5+[95]
An economical study was done by Peters et al to comparethe membrane system with amine scrubbing for natural gaspurification [96] The feed gas contained 95mol CO220 ppm H2S 10 ppm H2O and 724mol CH4 and theremaining for C2 to C6 The operating conditions were 60∘Cand 90 bar Results show that both technologies achievedthe sale gas specification of 4 ppm H2S and 2mol CO2however the treated gas by amine has better carbon dioxidepurity compared to themembrane but this was at the expenseof the capital investment It was concluded that themembranetechnology was still a better choice due to the environmentalissue related to solvent disposal
Another economical evaluation was performed by He etal and it confirmed that the membrane can replace aminescrubbing for natural gas treatment containing 10mol
carbon dioxide and lower [97] Natural gas processing cost bythe membrane system was 000573 $Nm3 which was 104less than amine scrubbing
5 Hydrogen Recovery
Hydrogen is a key element for many processes in the refinerysuch as hydrocracking and hydrotreating In hydrocrackinghydrogen is used to convert large hydrocarbons into smallerones in presence of a catalyst while in hydrotreating hydro-gen is used to remove sulfur compounds from fuels in theform of hydrogen sulfide [98] Furthermore hydrogen is afeedstock for many industries like ammonia synthesis andmethanol production [99]
Hydrogen is produced in the refinery by steam-methanereforming (SMR) where methane reacts with water to pro-duce hydrogen and carbon monoxide The produced gas iscalled syngas and hydrogen yield can be further increasedby the reaction of carbon monoxide with water to formhydrogen and carbon dioxide [100]
In petroleum industry hydrogen separation can be prac-ticed in the following processes (1) to recover some hydrogenduring natural gas production (2) to adjust hydrogen-to-carbon monoxide ratio (H2CO) in syngas (3) to recyclepart of hydrogen from hydrocracker and hydrotreatment tailgases (4) to separate hydrogen from nitrogen in ammoniaplant and (5) to purify hydrogen so it can be used as afeedstock for other industries [102ndash104] Content of hydrogenin refinery off-gases is given in Table 5
51 Current Technologies Mainly there are three methodsto separate hydrogen from gas mixtures (1) cryogenic dis-tillation (2) PSA and (3) membrane system The selectionof technology depends on feed composition product purityproduct flow rate reliability turndown and last but not leastcapital and operating costs Comparison between the threetechnologies is given in Table 6 As indicated the membranehas a better capability to treat a wider range of hydrogen from
International Journal of Polymer Science 7
Table 5 Hydrogen composition in refinery off-gases [101]
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
(i) Achieves gt99 of CO2 capture(ii) Produces liquefied CO2 for easier storage
(i) Economical only if the feed contains 50ndash70 CO2(ii) Higher pressure is required to avoid CO2 sublimation
Membranes(i) Requires minimum supervision(ii) Can remove H2S and H2O as well(iii) Long-operating life (gt5 years)
(i) High capital cost(ii) Pretreatment is required to remove particulates and some inhibitors
atmospheric pressure Unfortunately potassium carbonatehas lower sorption properties compared to amine and it ishighly corrosive [37 42]
Methanol can also be used for physical absorption ofcarbon dioxide and it has the highest selectivity compared toother solvents [39] The solvent can be regenerated by eitherreducing the pressure or increasing the temperature [40]Thefinal stream can have very low amounts of carbon dioxideof 10 ppm which is more efficient than amine scrubbingThe only disadvantage of this process is the high capitalinvestment [39]
Pressure swing adsorption (PSA) is another techniquefor carbon dioxide separation Unlike previous methodsPSA does not require a solvent The gas passes at a highpressure through a bed of activated carbon (also known ascarbon molecular sieve) and due to the difference in polarityadsorption of carbon dioxide will take place [72] The bedcan be regenerated by reducing the pressure to vacuumThe technique has an excellent separation performance andthe gas can have more than 90 methane purity and it isexpected to run for three years [73] Other PSA materialsare zeolite and alumina Disadvantages of this system arethe extensive energy for pressure cycle and low adsorptioncapacity compared to amine scrubbing [74]
Cryogenic distillation at very low temperature of minus84∘Cis efficient for carbon dioxide removal Because of the lowtriple point of carbon dioxide of minus57∘C at atmosphericpressure carbon dioxide will not have a liquid state and willsolidify directly [75] Therefore the distillation should takeplace at a pressure above 5 bar to overcome the triple pointlimitation otherwise carbon dioxide will cause blockageThe technology is used to liquify and produce high qualitystreams of carbon dioxide For the process to be economicalthe feed should contain 50 to 70 carbon dioxide and this isbecause of the high capital and operating costs of cryogenicdistillation [73] Unfortunately most of the refinery streamsdo not have that concentration of carbon dioxide [72]
In comparison with the above-mentioned the mem-branes have a unique feature as they can remove carbondioxide along hydrogen sulfide and water with one step [7677] In addition to low operating energy the membrane has along life and it can be operated continuously for at least 5 years
[78] However the operating life is greatly affected if partic-ulates were presented in the feed therefore pretreatment isneeded Table 3 shows the advantages and disadvantages ofdifferent methods for carbon dioxide capture
42 MembraneMaterials Removal of carbon dioxide startedwhen Robb studied in 1968 the diffusion of gases in PDMSmembrane [61] The work was expanded in 1989 when Sterndetermined the permeability coefficient of gases at highertemperature [17] CO2-permeable membranes are similar tothose that permeate hydrogen sulfide but the permeabil-ity differs due to the difference in sorption and diffusioncoefficients between carbon dioxide and hydrogen sulfideThe state-of-the-art materials for carbon dioxide separationare cellulose acetate polyamide polyimide and Pebax Asshown inTable 4 cellulose acetate has the lowest permeabilityof 24 Barrer but yet the selectivity of carbon dioxide tomethane (120572CO2CH4) reached 25 [25 50] Unfortunately pre-sence of heavy hydrocarbons in the feed caused a sig-nificant drop in the selectivity therefore cellulose acetatewas not suitable for fuel gas separation [50] Polyimideson the other hand show better thermal and chemical sta-bilities compared to cellulose acetate [2] These polymersare made from diacid with diamine in amic acid inter-mediate [79] Matrimid 5218 is a polyimide containingphenylindane group and it gives carbon dioxide permeabil-ity of 85 Barrer [1 80] This polymer shows outstandingselectivity of 28 and 367 for carbon dioxide to methane(120572CO2CH4) and carbon dioxide to nitrogen (120572CO2N2) respec-tively [81 82] Carbon dioxide permeability of polyimidecan be further enhanced by the introduction of fluo-ride Fluorinated polyimides are made using 22-bis(34-di-carboxyphenyl)hexafluoropropanedianhydride (6FDA) andthe permeability can be boosted to 456 Barrer [83 84]Copolymers like PUUand Pebax show also high permeabilityof 145 and 212 Barrer respectively [85 86] The rubberypolymer PDMS has an excellent permeability of 4000 Barrerbut the lowest carbon dioxide selectivity of 26 as given inTable 4
43 Commercial Units and Economical Evaluation Thelargest CO2-removal unit is manufactured by Cynara
6 International Journal of Polymer Science
Table 4 Permeability and selectivity of different polymers for carbon dioxide removal
(NATCO Group) for natural gas sweeting in an off-shorearea in Thailand The hollow fiber membrane is based oncellulose triacetate and capable of handling 830000Nm3h[25] Another system was installed to treat 120000Nm3h ofgas and it reduced carbon dioxide content from 80 to lessthan 10 [77 93]
Polaris membrane (made by MTR) was installed aftermethane-reforming unit and it successfully increased carbondioxide concentration from 20mol in the tail gas to morethan 90mol [26] The stream was used afterwards for wellinjection to enhance oil recovery Polaris membrane can alsotreat flue gases with excellent selectivity (120572CO2N2) of 50 [94]
UOP membranes are based on cellulose acetate and wereinstalled in Pakistan in 1995The systemworked continuouslyfor 12 years to cut down carbon dioxide concentration from65 to 2mol [63] The system was designed to process311950Nm3h of gas at 58 bar
UBE on the other hand developed a robust membrane forbetter stability under feed impurities The system is based onpolyimide membrane and it can work without any drop inperformance under the presence of 3mol hydrogen sulfidefull water saturation and heavy hydrogen carbons of C5+[95]
An economical study was done by Peters et al to comparethe membrane system with amine scrubbing for natural gaspurification [96] The feed gas contained 95mol CO220 ppm H2S 10 ppm H2O and 724mol CH4 and theremaining for C2 to C6 The operating conditions were 60∘Cand 90 bar Results show that both technologies achievedthe sale gas specification of 4 ppm H2S and 2mol CO2however the treated gas by amine has better carbon dioxidepurity compared to themembrane but this was at the expenseof the capital investment It was concluded that themembranetechnology was still a better choice due to the environmentalissue related to solvent disposal
Another economical evaluation was performed by He etal and it confirmed that the membrane can replace aminescrubbing for natural gas treatment containing 10mol
carbon dioxide and lower [97] Natural gas processing cost bythe membrane system was 000573 $Nm3 which was 104less than amine scrubbing
5 Hydrogen Recovery
Hydrogen is a key element for many processes in the refinerysuch as hydrocracking and hydrotreating In hydrocrackinghydrogen is used to convert large hydrocarbons into smallerones in presence of a catalyst while in hydrotreating hydro-gen is used to remove sulfur compounds from fuels in theform of hydrogen sulfide [98] Furthermore hydrogen is afeedstock for many industries like ammonia synthesis andmethanol production [99]
Hydrogen is produced in the refinery by steam-methanereforming (SMR) where methane reacts with water to pro-duce hydrogen and carbon monoxide The produced gas iscalled syngas and hydrogen yield can be further increasedby the reaction of carbon monoxide with water to formhydrogen and carbon dioxide [100]
In petroleum industry hydrogen separation can be prac-ticed in the following processes (1) to recover some hydrogenduring natural gas production (2) to adjust hydrogen-to-carbon monoxide ratio (H2CO) in syngas (3) to recyclepart of hydrogen from hydrocracker and hydrotreatment tailgases (4) to separate hydrogen from nitrogen in ammoniaplant and (5) to purify hydrogen so it can be used as afeedstock for other industries [102ndash104] Content of hydrogenin refinery off-gases is given in Table 5
51 Current Technologies Mainly there are three methodsto separate hydrogen from gas mixtures (1) cryogenic dis-tillation (2) PSA and (3) membrane system The selectionof technology depends on feed composition product purityproduct flow rate reliability turndown and last but not leastcapital and operating costs Comparison between the threetechnologies is given in Table 6 As indicated the membranehas a better capability to treat a wider range of hydrogen from
International Journal of Polymer Science 7
Table 5 Hydrogen composition in refinery off-gases [101]
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
(NATCO Group) for natural gas sweeting in an off-shorearea in Thailand The hollow fiber membrane is based oncellulose triacetate and capable of handling 830000Nm3h[25] Another system was installed to treat 120000Nm3h ofgas and it reduced carbon dioxide content from 80 to lessthan 10 [77 93]
Polaris membrane (made by MTR) was installed aftermethane-reforming unit and it successfully increased carbondioxide concentration from 20mol in the tail gas to morethan 90mol [26] The stream was used afterwards for wellinjection to enhance oil recovery Polaris membrane can alsotreat flue gases with excellent selectivity (120572CO2N2) of 50 [94]
UOP membranes are based on cellulose acetate and wereinstalled in Pakistan in 1995The systemworked continuouslyfor 12 years to cut down carbon dioxide concentration from65 to 2mol [63] The system was designed to process311950Nm3h of gas at 58 bar
UBE on the other hand developed a robust membrane forbetter stability under feed impurities The system is based onpolyimide membrane and it can work without any drop inperformance under the presence of 3mol hydrogen sulfidefull water saturation and heavy hydrogen carbons of C5+[95]
An economical study was done by Peters et al to comparethe membrane system with amine scrubbing for natural gaspurification [96] The feed gas contained 95mol CO220 ppm H2S 10 ppm H2O and 724mol CH4 and theremaining for C2 to C6 The operating conditions were 60∘Cand 90 bar Results show that both technologies achievedthe sale gas specification of 4 ppm H2S and 2mol CO2however the treated gas by amine has better carbon dioxidepurity compared to themembrane but this was at the expenseof the capital investment It was concluded that themembranetechnology was still a better choice due to the environmentalissue related to solvent disposal
Another economical evaluation was performed by He etal and it confirmed that the membrane can replace aminescrubbing for natural gas treatment containing 10mol
carbon dioxide and lower [97] Natural gas processing cost bythe membrane system was 000573 $Nm3 which was 104less than amine scrubbing
5 Hydrogen Recovery
Hydrogen is a key element for many processes in the refinerysuch as hydrocracking and hydrotreating In hydrocrackinghydrogen is used to convert large hydrocarbons into smallerones in presence of a catalyst while in hydrotreating hydro-gen is used to remove sulfur compounds from fuels in theform of hydrogen sulfide [98] Furthermore hydrogen is afeedstock for many industries like ammonia synthesis andmethanol production [99]
Hydrogen is produced in the refinery by steam-methanereforming (SMR) where methane reacts with water to pro-duce hydrogen and carbon monoxide The produced gas iscalled syngas and hydrogen yield can be further increasedby the reaction of carbon monoxide with water to formhydrogen and carbon dioxide [100]
In petroleum industry hydrogen separation can be prac-ticed in the following processes (1) to recover some hydrogenduring natural gas production (2) to adjust hydrogen-to-carbon monoxide ratio (H2CO) in syngas (3) to recyclepart of hydrogen from hydrocracker and hydrotreatment tailgases (4) to separate hydrogen from nitrogen in ammoniaplant and (5) to purify hydrogen so it can be used as afeedstock for other industries [102ndash104] Content of hydrogenin refinery off-gases is given in Table 5
51 Current Technologies Mainly there are three methodsto separate hydrogen from gas mixtures (1) cryogenic dis-tillation (2) PSA and (3) membrane system The selectionof technology depends on feed composition product purityproduct flow rate reliability turndown and last but not leastcapital and operating costs Comparison between the threetechnologies is given in Table 6 As indicated the membranehas a better capability to treat a wider range of hydrogen from
International Journal of Polymer Science 7
Table 5 Hydrogen composition in refinery off-gases [101]
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
30 to 90mol PSA comes first for the product purity ofover 99mol and cryogenic distillation is favorable to handlelarge volumes of 10000Nm3h and above Furthermore themembrane provides the best reliability where unexpectedshutdown occurs This is because the membrane does nothave mechanical parts whereas cryogenic distillation has thelowest reliability Turndown refers to a small change in theoperating condition and the membrane system is proven tobe the most stable For example a change in the feed pressurecan reduce the product purity in the membrane system by10 while PSA and cryogenic can be affected by 30 and 50respectively
52 MembraneMaterials Thefirst application of gas-separa-tion membranes was for hydrogen removal It was developedin 1970s by Monsanto (Air Products) to recover hydrogenfrom purge gas in ammonia plant [104ndash106] The spiral-wound membrane was based on polysulfone and it hasa permeability of 17 Barrer Cellulose acetate membraneswere introduced then by Separex and they showed a betterpermeability and stability therefore they were employed forremoval of hydrogen fromnatural gas [107]The permeabilitywas greatly improved from 14 to 24 Barrer when celluloseacetate was used instead of polysulfone For adjustment ofH2CO ratio in syngas polyimide (made by UBE) gave abetter permeation of 50 Barrer with superior selectivity ofH2CH4 (125) H2CO (50) and H2N2 (83) [1] ThoughPDMS givesmaximumhydrogen permeability of 1500 Barrerit has a low H2CH4 selectivity of unity making it unsuitablefor hydrogen separation from natural gas Furthermore it isreported that performance of PDMS membrane significantlydrops if carbon monoxide was presented in the feedstock[108] Table 7 shows hydrogen permeability and selectivity ofdifferent membrane materials
53 Commercial Units and Economical Evaluation Theworld-leading companies for hydrogen-permeable mem-branes are Air Products MTR UOP GENERON Praxairand UBE PRISM membrane (based on polysulfone anddeveloped by Air Products) is able to recover 90 to 98molof hydrogen from purge gas in ammonia plant [106] Themembrane can also upgrade hydrocracker off-gas streamcontaining 20ndash30mol hydrogen to 70ndash90mol in a singlestage or to 95molby two stages [114]The system is expectedto run for 7 years without any interruption
VaporSep membrane manufactured by MTR can recoverhydrogen from refinery waste gases The system can alsobe used to adjust H2CO ratio in syngas to meet the feedrequirement for different industries The system can handle
a feed pressure up to 170 bar with different concentrationsof 30ndash95mol of hydrogen with a maximum volume of235434Nm3hThepermeate is estimated to have a hydrogenpurity of 90ndash99mol [26] The system was installed in aKorean refinery to recover hydrogen from a hydrocracker off-gas and the unit improved the process economy and paiditself after only one month of operation
UOPPolySep is anothermembrane for hydrogen produc-tion that can treat refinery off-gases The membrane operatesat temperatures of 60 to 82∘C with feed pressures of 14 to170 bar Compared to VaporSep PolySep can handle largervolume of 412010Nm3hThe permeate pressure ranges from4 to 84 bar with hydrogen recovery of 70ndash98 [63]
Hydrogen recovery is considered economical if the wastegas contains 50mol hydrogen or more [106] Otherwiseproduction of hydrogen by SMR will be a better choicerather than separation A study was performed by Mivechianand Pakizeh to evaluate the feasibility of using a membranesystem to separate hydrogen from refinery off-gas containing72mol hydrogen with light hydrocarbons (C1ndashC6) Themembrane was based on polyimide and it showed a betterrecovery of 95 compared to 79 using PSAThemembranealso achieved a hydrogen purity of 983mol which is closeto PSA of 994molThe capital cost was almost the same forboth the membrane system and PSA [103]
6 Air Separation
Air contains 209mol of oxygen and 781mol of nitrogenand the remaining is for other gases such as argon andcarbon dioxide An increase in oxygen content (gt21mol)in the feed can improve the oxidation process due to thehigher flame temperatureThis raise in temperature is directlyrelated to the reduction in nitrogen content in the feed [19]Idea of using enriched oxygen for Claus process was initiatedin 1970s and then fully commercialized in 1985 in LakeCharles Refinery (US) by Goar Allison and Air Products [31]After hydrotreatment the sulfur-enriched gas is sent to Clausprocess to recover hydrogen sulfide in the formof solid sulfurThe concept of Claus process is based on oxidizing hydrogensulfide to sulfur and water
H2S +1
2O2 997888rarr S +H2O (7)
Because air is used to oxidize hydrogen sulfide presence ofnitrogen lowers the flame temperature and this could resultin the formation of ammonia salts too These salts cause apressure drop in the system Use of enriched oxygen insteadof air can greatly improve the capacity of sulfur removal andprevent salt formation For example use of 28mol oxygencan increase sulfur capacity up to 30 [115] Furthermore useof 45 oxygen nearly doubles the sulfur capacity
Oxygen enrichment can be beneficial for fluid catalyticcracking (FCC) unit as well This unit is used to breakdown large hydrocarbons (usually vacuum gas oil) to usefulproducts such as gasoline and dieselThe feed is first heated to315ndash427∘C and then enters a reactor where it gets in contactwith a catalyst [99]The catalyst is then regenerated thermally(to remove coke) by burning it with air However studies
8 International Journal of Polymer Science
Table 6 Comparison between current technologies for hydrogen recovery [105]
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
show that when 27mol of oxygen is used the capacity ofregenerating the catalyst increases by 10 to 15 In additionuse of enriched oxygen in furnaces can reduce nitrogencompounds (NO119909) and this will reduce the emissions [116]
61 Current Technologies Idea of using enriched oxygen infurnaces was practiced since 1930s for iron productionby cryogenic distillation [19] The process gives ultra-pureoxygen (gt999mol) by compressing air and then cooling itto a very low temperature below minus187∘C using a refrigerationcycle to liquify air After that it is sent to a distillation towerwhere oxygen leaves in the form of liquid and nitrogen in theform of gas due to the difference in boiling point [117]
PSA by zeolite can produce enriched oxygen within therange of 25 to 50mol oxygen [72] Actually both oxygenand nitrogen will be adsorbed on zeolite but nitrogen has ahigher adsorption rate thus the gas passing through zeolitewill have a higher content of oxygen Unfortunately due tolow adsorption rate of 002ndash008mol oxygen per one mol ofsorbent the process is not widely used [118]
Polymeric membrane is an alternative technology forair separation The technology has an advantage over cryo-genic distillation as it does not require cold temperaturesFurthermore the membrane does not need a regenerationstep same as PSA It is worthwhile to mention that ceramicmembranes made of ionic-electronic conducting materialsare capable of producing oxygen with 100 purity [119] Themechanism is based on oxygen vacancies that are createdat temperature of 800∘C and above [120] Unfortunately thetechnology is not yet commercialized due to many issuesrelated to sealing and instability due to presence of impuritiesin the feedstock making the polymeric membrane a solidchoice at the moment [121ndash123]
62 Membrane Materials Use of polymeric membranes foroxygen enrichment started in 1980s and it showed promisingresults compared to cryogenic distillation and PSA [124]The selection of membrane material relies on the selectivitytoward nitrogen (120572O2N2) It is stated that a selectivity ofat least 4 is needed for the membrane to compete withother technologies [125] List of materials meeting these cri-teria is cellulose acetate polysulfone polyamide polyimidepolyetherimide and poly(4-methyl-1-pentene) (TPX) [1 8291 126 127] As given in Table 8 polyetherimide shows thehighest selectivity of 82 yet lowest oxygen permeability of041 Barrer Polysulfone (PSF) has a better permeability of15 Barrer with very good selectivity of 58 and it is used infabrication of many commercial units [128] Poly(4-methyl-1-pentene) (TPX) is also used commercially and it has apermeability of 30 Barrer and good selectivity of 4 [128]
63 Commercial Units and Economical Evaluation UOPdev-eloped amembrane called SPIRAGAS that produces a streamcontaining 30mol of oxygen from air [128]Themembraneis based on a porous polysulfone coated with silicone andit has a spiral-wound module It operates at 21∘C and theproduct flow rate can reach up to 106Nm3h with feedpressure varying from 1 to 14 bar GENERON on the otherhand fabricated a membrane based on TPX and it gives ahigher oxygen content up to 35mol [129]
Moreover AVIRmembrane (manufactured by AGTech-nology Corporation) can produce 37 to 60mol of oxygen-enriched air [130] It should be mentioned that the mem-branes in Table 8 also produce a nitrogen-enriched streamin the retentate For example PRISM hollow fiber membrane(based on PDMS and made by Air Products) produces not
International Journal of Polymer Science 9
Table 8 Oxygen and nitrogen permeabilities of different polymeric materials
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
only enriched oxygen but also nitrogen with purity of 95ndash99mol The membrane operates at feed pressure of 55 to10 bar with volume flow rate up to 708Nm3h [131]
An economical analysis was done for the productionof 20 tons of enriched oxygen with 35mol purity usingvarious technologies [132] The comparison was based onpower requirement capital cost and operating cost andthe data is given in Table 9 As expected the membranecomes first in power requirement and it can save energyup to 49 and 38 compared to cryogenic distillation andPSA respectively The membrane also has the lowest capitalcost of 16000 to 27000 $ per tons of oxygen compared tocryogenic distillation and PSA Moreover the membranestill has the lowest operating cost of 23 $ton O2 whereascryogenic distillation needs 39 $tons O2 which is nearlydouble
7 Gas Dehydration
One of the issues in natural gas transport is the formation ofsolid hydrates These solids are formed due to the presenceof water and hydrocarbons at high pressure and low temper-ature [134] An example is methane hydrate with chemicalformula of CH4nH2O where 119899 is hydration number Thisparameter is used to determine hydrates in methane storagesand natural gas reserves [135] To prevent hydrate formationthe water content in natural gas should not exceed 104mg perm3 of natural gas [136]
71 Current Technologies Physical absorption by triethyleneglycol can be used to dehydrate natural gas However volatileorganic compounds (VOCs) will be formed during solventregeneration [137] Water removal by silica gel or activatedalumina is another technique where the wet gas enters adesiccant bed and water will be adsorbed [138] The bed issimply regenerated by heating and the adsorption process ismore effective compared to ethylene glycol
Molecular sieve by zeolite is widely used for removal ofwater from natural gas Compared to other desiccants zeolite(3A) can treat streams with wider range of relative humidity[139] Furthermore zeolite has a better chemical stability andis capable of adsorbing hydrogen sulfide and carbon dioxidemaking it a good choice for treating sour gas [140] Alsozeolite shows the highest adsorption capacities of 20 g H2Ogzeolite for streams having a relative humidity of 10 at 25∘C[141] With time zeolite will be saturated with water andthe bed can be regenerated by thermal regeneration (heatingto 200ndash300∘C) or reducing the pressure to vacuum [142]The drawback of zeolite is the higher energy requirementfor regeneration which is 16 more compared to silica andalumina [141]
Polymeric membrane not only removes water but alsoseparates hydrogen sulfide carbon dioxide and heavy hydro-carbons all in one step [63] The membrane is also expectedto run without interruption for many years However pre-treatment may be necessary to remove particulates from thefeed gas Unfortunately the technology is not suitable for
10 International Journal of Polymer Science
Table 10 Current technologies for dehydration of natural gas [141 150]
Technology Advantages Disadvantages
Glycol absorption(i) Continuous process(ii) Lower pressure drop compared to solid desiccants(iii) Better chemical stability
(i) Difficult to achieve water dew point below minus32∘C(ii) Harmful VOCs are formed during theregeneration of solvent
Alumina desiccant(i) Ability to adsorb heavy hydrocarbons(ii) Performance is nearly independent of the feed operatingcondition
(i) High pressure drop(ii) Regeneration is needed
Zeolite molecularsieving
(i) Ability to achieve dew point of minus101 to 149∘C(ii) Stable under sour gas (i) More energy is needed for regeneration
Polymericmembranes
(i) Ability to separate hydrogen sulfide carbon dioxide andheavy hydrocarbons (C3+) in one step(ii) Long life (7 years)(iii) No need for regeneration
(i) Pretreatment may be required(ii) Energy requirement for compressors(iii) Not suitable for large volume
Table 11 Water permeability of hydrophilic and hydrophobic membranes
Polymer 119875H2O (Barrer) 120572H2OCH4 T (∘C) RefHydrophobic membranes
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
treating large volume of natural gas due to economical issues[141] Table 10 shows the advantages and disadvantages ofeach process for water removal from natural gas
72 Membrane Materials Water separation membranes aredivided into two groups hydrophobic and hydrophilic mate-rials In hydrophobic membranes natural gas permeateswhile water is rejected Examples are polyimides and siliconerubbers particularly PDMS The latter have a water perme-ability of 45000 Barrer with water-to-methane selectivity(120572H2OCH4) of 38 [143 144] On the other hand hydrophilicmembranes are water permeable and some examples arepolysulfone and cellulose acetate As shown in Table 11hydrophilic membranes have higher water permeabilityand selectivity compared to hydrophobic membranes Forexample the water-permeable Pebax has a permeability of50000 Barrer which is 11 higher than PDMS [145 146]Nafion gives an outstanding permeability of 450000 Barrerand H2OCH4 selectivity of 4100000 It is a copolymerdeveloped by DuPont and made by the copolymerization oftetrafluoroethylene and perfluorovinyl with sulfonyl fluoride
termination step [147 148] Actually Nafion consists of ahydrophobic backbone (based on PolytetrafluoroethylenePTFE) and a hydrophilic sulfonated group that provides thetransport path for water [149]
73 Commercial Units and Economical Evaluation PRISM(Air Products) developed a water-permeable membrane forremoval of water from natural gas A unit was successfullyinstalled in Shell Nigeria to process 600000Nm3h of naturalgas [77]Themembrane is expected to be based on PDMS Asdiscussed previously FuelSep (MTR) is designed to removehydrogen sulfide from natural gas but it can also permeatecarbon dioxide and water GENERON also provides dehy-dration membranes and similar to FuelSep the membranepermeates hydrogen sulfide and carbon dioxide The systemcan work at operating condition up to 95 bar 71∘C and flowrate of 588586Nm3h [155]
Comparing the membrane with other separation meth-ods glycol absorption has the lowest capital cost followed byalumina adsorption zeolite molecular sieve and the mem-brane [141 150] On the other hand the membrane shows
International Journal of Polymer Science 11
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
Table 12 Comparison with different technologies for VOCs removal [27 159 160]
Technology VOC content Efficiency () Temperature (∘C) RemarksThermaloxidation 20 ppmndash20 LEL 95ndash99 371 (i) Energy recovery up to 85
(ii) Chlorinated compounds can form toxic gases
Catalyticoxidation 100ndash1000 90ndash98 149
(i) Energy recovery up to 70(ii) Efficiency is dependent on operating conditions(iii) Certain impurities can poison the catalyst
Activatedcarbon 700ndash10000 80ndash90 lt54 (i) Performance is greatly affected by moistures
(ii) Unstable in ketones aldehydes and estersMembranes lt20 ppmndash25 LEL 90ndash99 Ambient (i) Treated gas does not require further processing
the lowest operating cost For more details an economicalstudy was made by Binci et al to evaluate the membranesystem (PRISM) for natural gas dehydration [150] The studyalso included the implantation of glycol system The feedvolume varied from 20083 to 187500Nm3h and life spanwas 20 yearsThe feed was at 30 bar and 30∘CThemembranelifetime was assumed to be 10 years and accordingly it waschanged twice It was concluded that the membrane wascost effective for treating 20083 to 41667 Nm3h of gas Thesystem was considered uneconomical for treating more than41667 Nm3h of natural gas
8 Removal of VOC
Volatile organic compounds are liquids having a boiling pointof 50 to 260∘C [156] VOCs are carbon compounds thatreact with nitrogen oxides in the presence of sunlight toform harmful ozone in the atmosphere [157]Therefore fromenvironmental point of view VOCs need to be removedfrom air and industrial off-gases Some VOCs are valuablesolvents and recovery of these compounds is necessaryExamples of VOCs are acetone benzene formaldehydechlorofluorocarbons (CFCs) and hydrochlorofluorocarbons(HCFCs) [158]
81 Current Technologies Activated carbon thermal oxida-tion and catalytic oxidation are widely used to remove VOCsfrom gases Activated carbon is favorable to treat streamscontaining 700ndash10000 ppmVOCs and it is based on physicaladsorption [27] At high pressure VOCs will be adsorbedand carbon can be regenerated by reducing the pressureto vacuum On the other hand thermal oxidation is moresuitable for removing VOCs with higher concentration of20 ppm up to 20 of lower explosion limit (LEL) of the gasLEL is defined as the lowest concentration in which the gaswill produce fire in the presence of an ignition Going higherthan 20 LEL will generate excessive heat which may resultin an explosion [159]
In thermal oxidation the gas containing VOCs will beheated to a very high temperature of 760ndash871∘C where VOCswill be oxidized to carbon dioxide and water A catalyst canbe used to reduce the temperature to 316ndash538∘C and this pro-cess is called catalytic oxidation [160] The thermalcatalyticoxidation has an advantage over activated carbon as it canwithstand streams with high humidity However the system
is not suitable if chlorinated compounds were presentedThis is because chlorinated compounds will be incompletelycombusted and this leads to formation of toxic gases [161]The membrane technology overcomes this issue due to thehigh chemical stability [27 160] In addition the membranecan be operated under heavy moistures where activatedcarbon cannot be used [159] Furthermore the membraneworks at ambient temperature where other processes needelevated temperatures Table 12 compares current methodsfor VOCs removal
82 Membrane Materials Silicone rubbers like PDMS arewidely studied for removal of organic vapors from air Theserubbery polymers were tested for many VOCs like acetonebenzene toluene and xylene For acetone removal from airPDMS has a selectivity of 11 to 25 while for removal oftoluene PDSM has a higher selectivity of 83 as given inTable 13
Glassy polymers like polyimide were also evaluated forVOCs recovery Polyimide type PI 2080 (developed byUpjohn and based on condensation of 331015840441015840-benzophe-none tetracarboxylic dianhydride BDTA) was tested fordifferent VOCs such as methanol ethanol hexane tolueneand xylene [162] PI 2080 has a toluene-to-air selectivitymorethan double compared to PDMS Furthermore xylene-to-airselectivity is 9 times more in PI 2080 in comparison withPDMS
83 Commercial Units and Economical Evaluation MTRstarted installing VOC-recovery membranes for refineriesand petrochemical industries in 1992 The process was fea-sible for removal of VOCs in the range of 200 to 1000 ppmcontaining carbon tetrachloride First air containing VOCsis compressed to 13 bar to condense water and some of VOCsAfter that the stream enters two-stage membrane systemand VOCs permeate in the liquid form due to the use ofvacuum pump [27] Content of VOCs in the treated air willhave less than 10 ppm GKSS also developed a spiral-woundmembrane for VOCs removal and it is based on PDMS withpolyetherimide support [128]
Unfortunately there are some economical issues forselecting the membrane system for VOCs recovery and thisis related to high capital and operating costs A study wasdone on the removal of 1000 ppm VOCs from air withcapacity of 850Nm3h and it showed that the membrane
12 International Journal of Polymer Science
Table 13 Selectivity of various membranes from VOC separation from air (or N2 if stated)
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
requires a capital cost of 660000 $ whereas thermalcatalyticoxidation needs only 280000 $ [27] The activated carbonis also expected to have a capital cost less than 280000 $Thermalcatalytic oxidation achieved the lowest operatingcost of 15700 $month and it increased to 41000 $monthwhen the membrane system was used The activated carbonhas slightly higher operating cost of 45000 $month Thestudy is given in Table 14
Despite the excellent capital and operating costs ofthermalcatalytic oxidation the technology is not suitable totreat gases with volume less than 1699Nm3h In this caseactivated carbon or membrane system should be selectedActivated carbon is a better choice for treating low quantityof VOCs (eg 1000 ppm) but if the stream contains higherthan 10000 ppmVOCs the membrane is the winner becauseactivated carbon cannot be operated at these concentrations
9 LPG Recovery
Liquefied petroleum gas (LPG) containsmainly propane (C3)and butane (C4) The mixture is in the gas state at normalpressure but it becomes a liquid at moderate pressures [167]LPG is generally used as a source of heating and cookingand a fuel for vehicles [168] It is found in natural gas orproduced from crude oil LPG can also be recovered fromrefinery off-gases such as FCC overhead gas and PSA tail gas[26] Furthermore flare gases can have valuable amounts ofLPG
91 Current Technologies The dominant method to recoverLPG is by the combination of cryogenic cooling and gasexpansion (also known as turbo-expander) of natural gasFirst the gas is compressed and cooled to a very lowtemperature ofminus51∘C resulting in a partial condensation (coldbox process)The gas stream is then sent to a turbo-expanderin which the pressure is reduced and the temperature is
further decreased to minus91∘CThe liquid stream (from the coldbox process) passes through a throttle valve to decrease thetemperature to minus81∘C After that both streams are sent to ademethanizer unit to produce natural gas liquids (C2+) andrecover methane by distillation [33 169]
Before the invention of turbo-expander method in 1970sLPG was separated from natural gas by an absorption plantThe process uses a hydrocarbon solvent to physically removeLPG at low temperature of minus25∘C Due to the intensivemanpower and complexity of the technology the process wasreplaced with turbo-expander [169]
The membrane technology is recently applied for LPGrecovery Unlike turbo-expander the membrane is moreenergy-efficient because it operates at ambient temperatureIn addition it does not need the distillation step especially ifthe feedstock does not contain significant amount of heavierhydrocarbon (C5+)
92 Membrane Materials The concept of using the mem-brane for LPG recovery from refinery off-gases was intro-duced by ExxonMobil in 2006 [170] The membrane wasbased on a rubbery polymer which permeates propane andheavier hydrocarbons (C3+) but rejects hydrogen methaneand ethane [170] Polymers like polysiloxane and polybutadi-ene are suitable for LPG separation due to the high sorptionof C3+ compounds [170] Unfortunately few materials weretested for LPG removal and some of them are given inTable 15 PDMSmembrane gives propane and butane perme-abilities of 7400 and 14000 Barrer respectively [171 172] Onthe other hand poly[1-(trimethylsilyl)-1-propyne] (PTMSP)shows interesting permeabilities of 33800 and 53500 Barrerfor propane and butane [173 174]
93 Commercial Units and Economical Evaluation MTRdeveloped a membrane system called LPG-SEP to recover
International Journal of Polymer Science 13
Table 14 Economical study for removal of VOCs (1000 ppm) from air to treat 850Nm3h by different technologies [27]
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
LPG from natural gas containing heavy hydrocarbons (asso-ciated petroleum gas) [26 177]This stream sometimes needsto be flared thus wasting valuable products and causingincrease in carbon dioxide emissions In LPG-SEP processassociated gas is compressed to 24 bar and then cooled to 16∘Cto condense hydrocarbons of propane and above (C3+)Thesehydrocarbons are then sent to a fractionator (distillationcolumn) to separate LPGThe compressed associated gas willenter a membrane that permeates methane to recover naturalgas This membrane system can handle 2354ndash58858Nm3hof gas with natural gas content of 5 to 50mol LPG recoverycan reach 95 with payback of 6 to 18 months [26]
MTR also developed amembrane called VaporSep whichcan be used to separate LPG from flare gas FCC overheadgas and PSA tail gas [26] As a case study a Texas refineryhad an issue with excess flare gas that contains valuableamounts of hydrogen andLPGTheproblemwas evaluated bythe installation of a compression-condensation-membranecombination system The flare gas was first compressed andcondensed to recover some of LPG After that the gas entersamembrane system to separate LPG fromhydrogenThe unitwas designed to handle 93Nm3h of LPG and payback wasless than a year [26]
As discussed the membrane technology needs to beintegrated with conventional methods if the stream containssignificant amounts of C5+ This is because the membranepermeates C3 and above and the permeability increases withcarbon number Therefore it is not possible to produceLPG from a stream containing C3 to C5+ and therefore adistillation column will be required to separate C3 and C4from C5+ However the membrane will be a good separationtechnique if the stream contains LPG only with other gasessuch as hydrogen or carbon dioxide
10 Conclusion
In this paper applications of polymeric membranes inthe refinery were discussed The membranes are currentlyimplemented for hydrogen sulfide separation carbon dioxidecapture hydrogen recovery air separation gas dehydrationVOCs removal and LPG recovery For hydrogen sulfide
separation cellulose acetate is widely used as a membranematerial and the processing cost for natural gas treatmentwas lower compared to amine scrubbing to treat naturalgas with 1mol of hydrogen sulfide For carbon dioxidecapture polyimide membrane has an advantage over othertechnologies as it can remove hydrogen sulfide and waterin one step The membrane also shows lower capital costscompared to conventional methods For hydrogen recoverypolyimide membrane can be used to recover hydrogen fromnatural gas and refinery off-gases However the process isconsidered economical only if hydrogen content is higherthan 50mol in the waste gas In air separation use ofenriched oxygen can improve the capacity of Claus andFCC units Polysulfone membranes were used to produce35mol oxygen and the technology has reduced the powerrequirement by 49 compared to cryogenic distillation Forgas dehydration water needs to be removed from naturalgas to avoid solid hydrates formation This is usually doneby glycol absorption but the process results in formation oftoxic VOC The membrane not only eliminates this issuebut also removes other natural gas impurities FurthermorePDMS membrane was proven to be cost effective comparedto glycol absorption for treating 20083 to 41667Nm3h ofnatural gas VOCs are usually found in waste gases and someof VOCs are expensive solvents Recovery of these VOCsis a must due to environmental and economical issues Themembrane technology is unique for that application as it candeal with feeds containing halogens andmoistures Howeverhigh capital and operating costs negatively affect the selectionof this technology compared to thermalcatalytic oxidationIn the refinery LPG is recovered from natural gas andwaste gases Combination of cryogenic distillation and gasexpansion is widely used to separate LPG The membranestill cannot substitute the current technology but it can beintegrated to eliminate the cryogenic step as it operates atambient temperature and this will greatly reduce the energyrequirement
One issue of the membrane technology is the sensitivityto impurities in the feedstock Cellulose acetate can be usedfor many applications such as acid gas removal hydrogenrecovery and air separation but presence of water and
14 International Journal of Polymer Science
Table 16 Summary of gas separation processes in the refinery and advantages of using membranes
Process Separation Applications Current technologies Advantages of membranes Membrane materials
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
(i) Can separate CO2 with otherimpurities such as H2S and H2O(ii) Can be operated continuouslyfor more than 5 years(iii) Low NG processing cost forfeed with lt10mol CO2
hydrocarbons can negatively affect the membrane perfor-mance Therefore the membrane should be tested underreal feeds to insure the membrane stability for long-termoperation Summary of this paper is given in Table 16
Competing Interests
The authors declare that they have no competing interests
References
[1] R BakerMembrane Technology and Applications JohnWiley ampSons 2012
[2] A Ismail K Khulbe and T Matsuura Gas Separation Mem-branes Polymeric and Inorganic Springer 2015
[3] M Stewart and K Arnold Gas Sweetening and Processing FieldManual Gulf Professional Publishing 2011
[4] A Ismail and T Matsuura Sustainable Membrane Technologyfor Energy Water and Environment John Wiley amp Sons 2012
[5] P Ball ldquoScale-up and scale-down of membrane-based separa-tion processesrdquoMembrane Technology vol 2000 no 117 pp 10ndash13 2000
[6] A Basile and F Gallucci Membranes for Membrane ReactorsPreparation Optimization and Selection John Wiley amp Sons2011
[7] B K Nandi R Uppaluri and M K Purkait ldquoPreparation andcharacterization of low cost ceramic membranes for micro-filtration applicationsrdquo Applied Clay Science vol 42 no 1-2 pp102ndash110 2008
[8] D Green and R Perry Perryrsquos Chemical Engineersrsquo HandbookMcGraw-Hill Education 8th edition 2007
[9] L Gandia G Arzamedi and P Dieguez Renewable HydrogenTechnologies Production Purification Storage Applications andSafety Elsevier Science 2013
[10] S Loeb and S Sourirajan ldquoSeawater demineralization bymeansof a semipermeable membranerdquoAdvances in Chemistry vol 38pp 117ndash132 1962
[11] L Petheram Acid Rain Bridgestone Books 2002
International Journal of Polymer Science 15
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
[12] L Sidney and S Srinivasa ldquoHigh flow porous membranes forseparating water from saline solutionsrdquo US Patent 31331321964
[13] P K Gantzel and U Merten ldquoGas separations with high-fluxcellulose acetate membranesrdquo Industrial amp Engineering Chem-istry vol 9 no 2 pp 331ndash332 1970
[14] S A Stern J T Mullhaupt and P J Gareis ldquoThe effect of pre-ssure on the permeation of gases and vapors through polyethy-lene usefulness of the corresponding states principlerdquo AIChEJournal vol 15 no 1 pp 64ndash73 1969
[15] J M S Henis and M K Trinodi ldquoA novel approach to gas sep-arations using composite hollow fiber membranesrdquo SeparationScience and Technology vol 15 no 4 pp 1059ndash1068 1980
[16] R W Baker ldquoFuture directions of membrane gas separationtechnologyrdquo Industrial and Engineering Chemistry Research vol41 no 6 pp 1393ndash1411 2002
[17] G George N Bhoria S Alhallaq A Abdala and V MittalldquoPolymer membranes for acid gas removal from natural gasrdquoSeparation and Purification Technology vol 158 pp 333ndash3562016
[18] A Figoli A Cassano and A BasileMembrane Technologies forBiorefining Elsevier Science 2016
[19] C Baukal Oxygen-Enhanced Combustion CRC Press 2010[20] Z R Ismagilov ldquoPorous alumina as a support for catalysts
and membranes Preparation and studyrdquo Reaction Kinetics andCatalysis Letters vol 60 no 2 pp 225ndash231 1997
[21] J G Wijmans and R W Baker ldquoThe solution-diffusion modela reviewrdquo Journal of Membrane Science vol 107 no 1-2 pp 1ndash211995
[22] B D Freeman ldquoBasis of permeabilityselectivity tradeoff rela-tions in polymeric gas separationmembranesrdquoMacromoleculesvol 32 no 2 pp 375ndash380 1999
[23] J Cowie Polymers Chemistry and Physics of Modern MaterialsTaylor amp Francis 2nd edition 1991
[24] L M Robeson Q Liu B D Freeman and D R PaulldquoComparison of transport properties of rubbery and glassypolymers and the relevance to the upper bound relationshiprdquoJournal of Membrane Science vol 476 pp 421ndash431 2015
[25] P Bernardo E Drioli and G Golemme ldquoMembrane gasseparation a reviewstate of the artrdquo Industrial and EngineeringChemistry Research vol 48 no 10 pp 4638ndash4663 2009
[26] Membrane Research and Technology (MTR) httpwwwmtr-inccom
[27] US Department of Energy ldquoMembrane system for the recoveryof volatile organic compounds from remediation off-gasesrdquoInnovative Technology Summary Report US Department ofEnergy 2001
[28] C Kent Basics of Toxicology John Wiley amp Sons 1998[29] B Sharma Environmental Chemistry Krishna Prakashan 2007[30] Q Acton Noncarboxylic Acidsadvances in Research and Appli-
cation Scholarly Editions 2013[31] A L Kohl and R Nielsen Gas Purification Elsevier 1997[32] P Lens and L Pol Environmental Technologies to Treat Sulfur
Pollution Principles and Engineering IWA Publishing 2000[33] J McKetta Encyclopedia of chemical processing and design
Volume 28mdashLactic Acid to Magnesium Supply-Demand Rela-tionships Taylor amp Francis 1988
[34] M Mork and J Gudmundsson ldquoNatural gas cleaningrdquo NaturalGas vol 3 p 44 2011
[35] M GhatiNatural Gas Cleanining Norwegian University of Sci-ence and Technology Department of Petroleum Engineeringand Applied Geophysics 2013
[36] R Sadeghbeigi Fluid Catalytic Cracking Handbook DesignOperation and Troubleshooting of FCC Facilities Gulf Publish-ing 2000
[37] S LeeMethane and Its Derivatives Taylor amp Francis 1996[38] R Faiz K Li and M Al-Marzouqi ldquoH2S absorption at high
pressure using hollow fibre membrane contactorsrdquo ChemicalEngineering and Processing Process Intensification vol 83 pp33ndash42 2014
[39] T Hignett Fertilizer Manual Springer Netherlands 2013[40] A Rojey Gas Cycling A New Approach Editions Technip 1999[41] T Lieuwen R Yetter and V Yang Synthesis Gas Combustion
Fundamentals and Applications CRC Press 2009[42] P Feron Absorption-Based Post-Combustion Capture of Carbon
Dioxide Elsevier Science 2016[43] J Marko Mass Transfer in Chemical Engineering Processes
InTech 2011[44] P Poltronieri and O DrsquoUrso Biotransformation of Agricultural
[45] N Abatzoglou and S Boivin ldquoA review of biogas purificationprocessesrdquo Biofuels Bioproducts and Biorefining vol 3 no 1 pp42ndash71 2009
[46] T Flynn Cryogenic Engineering CRC Press 2nd edition 2004[47] N Mitra Fundamentals of Floating Production Systems Allied
Publishers 2009[48] J-M Nhut R Vieira L Pesant et al ldquoSynthesis and catalytic
uses of carbon and silicon carbide nanostructuresrdquo CatalysisToday vol 76 no 1 pp 11ndash32 2002
[49] J Crespo and K Boddeker Membrane Processes in Separationand Purification Springer 2013
[50] G Chatterjee A A Houde and S A Stern ldquoPoly(etherurethane) and poly(ether urethane urea) membranes with highH2SCH4 selectivityrdquo Journal of Membrane Science vol 135 no1 pp 99ndash106 1997
[51] M Al-Juaied and W J Koros ldquoPerformance of natural gasmembranes in the presence of heavy hydrocarbonsrdquo Journal ofMembrane Science vol 274 no 1-2 pp 227ndash243 2006
[52] K Hunger N Schmeling H B T Jeazet C Janiak CStaudt and K Kleinermanns ldquoInvestigation of cross-linkedand additive containing polymer materials for membranes withimproved performance in pervaporation and gas separationrdquoMembranes vol 2 no 4 pp 727ndash763 2012
[53] S KelmanCrosslinking and Stabilization of High Fractional FreeVolume Polymers for the Separation of Organic Vapors fromPermanent Gases University of Texas at Austin 2008
[54] H Li B D Freeman and O M Ekiner ldquoGas permeation prop-erties of poly(urethane-urea)s containing different polyethersrdquoJournal of Membrane Science vol 369 no 1-2 pp 49ndash58 2011
[55] S Sridhar B Smitha S Mayor B Prathab and T M Aminab-havi ldquoGas permeation properties of polyamide membraneprepared by interfacial polymerizationrdquo Journal of MaterialsScience vol 42 no 22 pp 9392ndash9401 2007
[56] J Chen Evaluation of Polymeric Membranes for Gas SeparationProcesses Poly(ether-b-amide) (PEBAX 2533) Block CopolymerUniversity of Waterloo 2002
[57] V I Bondar B D Freeman and I Pinnau ldquoGas transport prop-erties of poly(ether-b-amide) segmented block copolymersrdquo
16 International Journal of Polymer Science
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
Journal of Polymer Science Part B Polymer Physics vol 38 no15 pp 2051ndash2062 2000
[58] J T Vaughn W J Koros J R Johnson and O Karvan ldquoEffectof thermal annealing on a novel polyamide-imide polymermembrane for aggressive acid gas separationsrdquo Journal ofMembrane Science vol 401-402 pp 163ndash174 2012
[59] J T Vaughn and W J Koros ldquoAnalysis of feed stream acidgas concentration effects on the transport properties andseparation performance of polymeric membranes for naturalgas sweetening a comparison between a glassy and rubberypolymerrdquo Journal of Membrane Science vol 465 pp 107ndash1162014
[60] O V Malykh A Y Golub and V V Teplyakov ldquoPolymericmembrane materials new aspects of empirical approachesto prediction of gas permeability parameters in relation topermanent gases linear lower hydrocarbons and some toxicgasesrdquo Advances in Colloid and Interface Science vol 164 no1-2 pp 89ndash99 2011
[61] W L Robb ldquoThin silicone membranes-their permeation prop-erties and some applicationsrdquo Annals of the New York Academyof Sciences vol 146 no 1 pp 119ndash137 1968
[62] R Rousseau Handbook of Separation Process Technology JohnWiley amp Sons 1987
[63] Universal Oil Products (UOP) httpswwwuopcom[64] B D Bhide and S A Stern ldquoMembrane processes for the
removal of acid gases from natural gas II Effects of operatingconditions economic parameters and membrane propertiesrdquoJournal of Membrane Science vol 81 no 3 pp 239ndash252 1993
[65] J Andrews N Jelley and N Jelley Energy Science PrinciplesTechnologies and Impacts OUP Oxford 2013
[66] R Durie P McMullan C Paulson A Smith and D WilliamsGreenhouse Gas Control Technologies Proceedings of the 5thInternational Conference on Greenhouse Gas control Technolo-gies CSIRO Publishing 2001
[67] M Aresta Carbon Dioxide Recovery and Utilization Springer2013
[68] I S Cole P Corrigan S Sim and N Birbilis ldquoCorrosion ofpipelines used for CO2 transport in CCS is it a real problemrdquoInternational Journal of Greenhouse Gas Control vol 5 no 4pp 749ndash756 2011
[69] L F Drbal P G Boston and K L Westra Power PlantEngineering Springer US Boston Mass USA 1996
[70] M Islamiyah T Soehartanto R Hantoro and A Abdurrah-man ldquoWater scrubbing for removal of CO2 (carbon dioxide)and H2S (hydrogen sulfide) in biogas from manurerdquo KnEEnergy vol 2 no 2 pp 126ndash131 2015
[71] D Sanyal N Vasishtha and D N Saraf ldquoModeling of carbondioxide absorber using hot carbonate processrdquo Industrial andEngineering Chemistry Research vol 27 no 11 pp 2149ndash21561988
[72] S Auerbach K Carrado and P Dutta Handbook of ZeoliteScience and Technology CRCPress Boca Raton Fla USA 2003
[73] H Al-Megren Advances in Natural Gas Technology InTech2012
[74] D Thomas and S Benson Carbon Dioxide Capture for Storagein Deep Geologic FormationsmdashResults from the CO2 CaptureProject Elsevier Science 2005
[75] J Wilcox Carbon Capture Springer 2012[76] S Gaspard and M Ncibi Biomass for Sustainable Applications
Pollution Remediation and Energy Royal Society of Chemistry2013
[77] E M Hoek and V V Tarabara Encyclopedia of MembraneScience and Technology JohnWiley amp Sons Hoboken NJ USA2013
[78] X He J Lie E Sheridan and M-B Hagg ldquoCO2 captureby hollow fibre carbon membranes experiments and processsimulationsrdquo Energy Procedia vol 1 no 1 pp 261ndash268 2009
[79] D Kemmish High Performance Engineering Plastics RapraTechnology Limited 1995
[80] O Ekiner and R Hayes ldquoPhenylindane-containing polyimidegas separation membranesrdquo European Patent EP0422885B11994
[81] O C David D Gorri K Nijmeijer I Ortiz and A UrtiagaldquoHydrogen separation frommulticomponent gas mixtures con-taining CO N2 and CO2 using Matrimid asymmetric hollowfiber membranesrdquo Journal of Membrane Science vol 419-420pp 49ndash56 2012
[82] Y Huang and D R Paul ldquoEffect of film thickness on thegas-permeation characteristics of glassy polymer membranesrdquoIndustrial and Engineering Chemistry Research vol 46 no 8 pp2342ndash2347 2007
[83] S L Liu R Wang Y Liu M L Chng and T S Chung ldquoThephysical and gas permeation properties of 6FDA-durene26-diaminotoluene copolyimidesrdquo Polymer vol 42 no 21 pp8847ndash8855 2001
[84] D F Sanders Z P Smith R Guo et al ldquoEnergy-efficientpolymeric gas separation membranes for a sustainable futurea reviewrdquo Polymer vol 54 no 18 pp 4729ndash4761 2013
[85] M Sadeghi H T Afarani and Z Tarashi ldquoPreparation andinvestigation of the gas separation properties of polyurethane-TiO2 nanocomposite membranesrdquo Korean Journal of ChemicalEngineering vol 32 no 1 pp 97ndash103 2014
[86] C A Scholes G Q Chen H T Lu and S E KentishldquoCrosslinked PEG and PEBAX membranes for concurrentpermeation of water and carbon dioxiderdquo Membranes vol 6no 1 article 1 2015
[87] B Flaconneche J Martin and M H Klopffer ldquoPermeabilitydiffusion and solubility of gases in polyethylene polyamide11 and poly (vinylidene fluoride)rdquo Oil amp Gas Science andTechnology vol 56 no 3 pp 261ndash278 2001
[88] C L Aitken W J Koros and D R Paul ldquoEffect of structuralsymmetry on transport properties of polysulfonesrdquo Macro-molecules vol 25 no 13 pp 3424ndash3434 1992
[89] W J Koros A H Chan andD R Paul ldquoSorption and transportof various gases in polycarbonaterdquo Journal ofMembrane Sciencevol 2 pp 165ndash190 1977
[90] M Calle A E Lozano J de Abajo J G de la Campa and CAlvarez ldquoDesign of gas separation membranes derived of rigidaromatic polyimides 1 Polymers from diamines containing di-tert-butyl side groupsrdquo Journal of Membrane Science vol 365no 1-2 pp 145ndash153 2010
[91] W J Koros G K Fleming S M Jordan T H Kim and H HHoehn ldquoPolymeric membrane materials for solution-diffusionbased permeation separationsrdquo Progress in Polymer Science vol13 no 4 pp 339ndash401 1988
[92] M Sadrzadeh K Shahidi and T Mohammadi ldquoSynthesis andgas permeation properties of a single layer PDMS membranerdquoJournal of Applied Polymer Science vol 117 no 1 pp 33ndash48 2010
[93] R Bounaceur N Lape D Roizard C Vallieres and E FavreldquoMembrane processes for post-combustion carbon dioxidecapture a parametric studyrdquo Energy vol 31 no 14 pp 2556ndash2570 2006
International Journal of Polymer Science 17
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
[94] Y Chen and W S W Ho ldquoHigh-molecular-weight polyviny-laminepiperazine glycinate membranes for CO2 capture fromflue gasrdquo Journal of Membrane Science vol 514 pp 376ndash3842016
[95] UBE Industries httpwwwubecoth[96] L Peters A Hussain M Follmann T Melin and M-B Hagg
ldquoCO2 removal from natural gas by employing amine absorptionandmembrane technologymdasha technical and economical analy-sisrdquoChemical Engineering Journal vol 172 no 2-3 pp 952ndash9602011
[97] X He M-B Hagg and T-J Kim ldquoHybrid FSC membranefor CO2 removal from natural gas experimental processsimulation and economic feasibility analysisrdquo AIChE Journalvol 60 no 12 pp 4174ndash4184 2014
[98] A Klerk Fischer-Tropsch Refining Wiley-VCH 2011[99] M Fahim T Al-Sahhaf and A Elkilani Fundamentals of
Petroleum Refining Elsevier Science 2009[100] C Padro and F Lau Advances in Hydrogen Energy Springer
2007[101] A M Aitani ldquoProcesses to enhance refinery-hydrogen produc-
tionrdquo International Journal of Hydrogen Energy vol 21 no 4 pp267ndash271 1996
[102] K Blok R H Williams R E Katofsky and C A HendriksldquoHydrogen production fromnatural gas sequestration of recov-ered CO2 in depleted gas wells and enhanced natural gasrecoveryrdquo Energy vol 22 no 2-3 pp 161ndash168 1997
[103] AMivechian andM Pakizeh ldquoHydrogen recovery fromTehranrefinery off-gas using pressure swing adsorption gas absorptionand membrane separation technologies simulation and eco-nomic evaluationrdquoKorean Journal of Chemical Engineering vol30 no 4 pp 937ndash948 2013
[104] N W Ockwig and T M Nenoff ldquoMembranes for hydrogenseparationrdquo Chemical Reviews vol 107 no 10 pp 4078ndash41102007
[105] E Drioli G Barbieri and L M Peter Membrane Engineeringfor the Treatment of Gases Gas-separation Problems with Mem-branes Royal Society of Chemistry 2011
[106] B Tarasov and M Lototskii ldquoHydrogen for energy productionproblems and perspectivesrdquo International Social Science Journalvol 8 no 40 pp 72ndash90 2006
[107] W Schell and C Houston Spiral-Wound Permeators for Purifi-cations and Recovery vol 78 Chemical Engineering Progress1982
[108] C A Scholes G W Stevens and S E Kentish ldquoThe effectof hydrogen sulfide carbon monoxide and water on the per-formance of a PDMS membrane in carbon dioxidenitrogenseparationrdquo Journal of Membrane Science vol 350 no 1-2 pp189ndash199 2010
[109] C Liu and S Wilson ldquoMixed matrix membranes incorporatingmicroporous polymers as fillersrdquo Patent WO2010002404 A12010
[110] M G Shalygin S M Abramov A I Netrusov and V VTeplyakov ldquoMembrane recovery of hydrogen from gaseousmixtures of biogenic and technogenic originrdquo InternationalJournal of Hydrogen Energy vol 40 no 8 pp 3438ndash3451 2015
[111] C J Orme M L Stone M T Benson and E S PetersonldquoTesting of polymer membranes for the selective permeabilityof hydrogenrdquo Separation Science and Technology vol 38 no 12-13 pp 3225ndash3238 2003
[112] W Browall ldquoUltrathin polyetherimide membrane and gasseparation processrdquo US Patent 4156597 1979
[113] A Alentiev E Drioli M Gokzhaev et al ldquoGas permeationproperties of phenylene oxide polymersrdquo Journal of MembraneScience vol 138 no 1 pp 99ndash107 1998
[114] PRISM membrane systems for oil refinery applications (cata-logue) Air Products 2016
[115] S Mokhatab W Poe and J Mak Handbook of Natural GasTransmission and Processing Principles and Practices ElsevierScience 2015
[116] H LinM Zhou J Ly et al ldquoMembrane-based oxygen-enrichedcombustionrdquo Industrial amp Engineering Chemistry Research vol52 no 31 pp 10820ndash10834 2013
[117] T Burdyny and H Struchtrup ldquoHybrid membranecryogenicseparation of oxygen from air for use in the oxy-fuel processrdquoEnergy vol 35 no 5 pp 1884ndash1897 2010
[118] S Sircar and B F Hanley ldquoProduction of oxygen enriched airby rapid pressure swing adsorptionrdquo Adsorption vol 1 no 4pp 313ndash320 1995
[119] X Tan Z Pang and K Li ldquoOxygen production usingLa06Sr04Co02Fe08O3minus120572 (LSCF) perovskite hollow fibre mem-brane modulesrdquo Journal of Membrane Science vol 310 no 1-2pp 550ndash556 2008
[120] A Hunt G Dimitrakopoulos and A F Ghoniem ldquoSurfaceoxygen vacancy andoxygenpermeationflux limits of perovskiteion transport membranesrdquo Journal of Membrane Science vol489 pp 248ndash257 2015
[121] A Leo S Liu and J C D D Costa ldquoDevelopment ofmixed conducting membranes for clean coal energy deliveryrdquoInternational Journal of Greenhouse Gas Control vol 3 no 4pp 357ndash367 2009
[122] W Yang HWang X Zhu and L Lin ldquoDevelopment and appli-cation of oxygen permeable membrane in selective oxidation oflight alkanesrdquo Topics in Catalysis vol 35 no 1-2 pp 155ndash1672005
[123] HWang P Kolsch T Schiestel C Tablet SWerth and J CaroldquoProduction of high-purity oxygen by perovskite hollow fibermembranes swept with steamrdquo Journal of Membrane Sciencevol 284 no 1-2 pp 5ndash8 2006
[124] P Pandey and R S Chauhan ldquoMembranes for gas separationrdquoProgress in Polymer Science vol 26 no 6 pp 853ndash893 2001
[125] W J Koros and R Mahajan ldquoPushing the limits on possibilitiesfor large scale gas separation which strategiesrdquo Journal ofMembrane Science vol 175 no 2 pp 181ndash196 2000
[126] B D Reid F A Ruiz-Trevino I H Musselman K J Balkus Jrand J P Ferraris ldquoGas permeability properties of polysulfonemembranes containing themesoporousmolecular sieveMCM-41rdquo Chemistry of Materials vol 13 no 7 pp 2366ndash2373 2001
[127] J Espeso A E Lozano J G de la Campa and J deAbajo ldquoEffectof substituents on the permeation properties of polyamidemembranesrdquo Journal of Membrane Science vol 280 no 1-2 pp659ndash665 2006
[128] T Matsuura Synthetic Membranes and Membrane SeparationProcesses Taylor amp Francis 1993
[129] K McReynolds ldquoGeneron air separation systems-membranesin gas separation and enrichmentrdquo inProceedings of the 4th BOCPriestley Conference pp 342ndash350 Royal Society of Chemistry1986
[130] L Romano C Gottzmann D Thompson and R PrasadldquoNitrogen production using membranesrdquo in Proceedings ofthe 7th Annual Membrane TechnologyPlanning Conferencepp 144ndash154 Business Communications Co Cambridge MassUSA November 1989
18 International Journal of Polymer Science
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
[131] E Beaver ldquoPERMEA-gas separationmembranes developed intoa commercial realityrdquo in Proceedings of the 7th Annual Mem-brane TechonologyPlanning Conference pp 144ndash154 BusinessCommunications 1989
[132] A G a M KIeper ldquoThe economics of oxygen enriched airproduction via membranesrdquo in Proceedings of the 6th AnnualIndustrial Energy Technology Conference vol 1 pp 298ndash3061984
[133] K Scott and R Hughes Industrial Membrane Separation Tech-nology Springer Netherlands 2012
[134] R W Baker and K Lokhandwala ldquoNatural gas processing withmembranes an overviewrdquo Industrial amp Engineering ChemistryResearch vol 47 no 7 pp 2109ndash2121 2008
[135] Y Ye andC LiuNatural GasHydrates Experimental Techniquesand Their Applications Springer 2012
[136] H Lin S M Thompson A Serbanescu-Martin et al ldquoDehy-dration of natural gas using membranes Part I compositemembranesrdquo Journal of Membrane Science vol 413-414 pp 70ndash81 2012
[137] A Kidnay W Parrish and D McCartney Fundamentals ofNatural Gas Processing CRC Press 2011
[138] H A A Farag M M Ezzat H Amer and A W NashedldquoNatural gas dehydration by desiccant materialsrdquo AlexandriaEngineering Journal vol 50 no 4 pp 431ndash439 2011
[139] S Kulprathipanja Zeolites in Industrial Separation and Cataly-sis John Wiley amp Sons 2010
[140] M Ozekmekci G Salkic and M F Fellah ldquoUse of zeolites forthe removal of H2S a mini-reviewrdquo Fuel Processing Technologyvol 139 pp 49ndash60 2015
[141] F Manning and R Thompson Oilfield Processing of PetroleumNatural Gas PennWell Books 1991
[142] A Ntiamoah J Ling P Xiao P A Webley and Y Zhai ldquoCO2capture by temperature swing adsorption use of hot CO2-rich gas for regenerationrdquo Industrial amp Engineering ChemistryResearch vol 55 no 3 pp 703ndash713 2016
[143] J Barrie 4th BOC Priestley Conference Membranes in GasSeparation and Enrichment UK Royal Society of Chemistry1986
[144] T C Merkel V I Bondar K Nagai B D Freeman and IPinnau ldquoGas sorption diffusion and permeation in poly(di-methylsiloxane)rdquo Journal of Polymer Science Part B PolymerPhysics vol 38 no 3 pp 415ndash434 2000
[145] J Potreck K Nijmeijer T Kosinski and M Wessling ldquoMixedwater vaporgas transport through the rubbery polymerPEBAX 1074rdquo Journal of Membrane Science vol 338 no 1-2pp 11ndash16 2009
[146] V Barbi S S Funari R Gehrke N Scharnagl and N StribeckldquoSAXS and the gas transport in polyether-block-polyamidecopolymermembranesrdquoMacromolecules vol 36 no 3 pp 749ndash758 2003
[147] J S Chiou and D R Paul ldquoGas permeation in a dry nafionmembranerdquo Industrial and Engineering Chemistry Research vol27 no 11 pp 2161ndash2164 1988
[148] K A Mauritz and R B Moore ldquoState of understanding ofNafionrdquoChemical Reviews vol 104 no 10 pp 4535ndash4586 2004
[149] T D Gierke G E Munn and F C Wilson ldquoThe morphologyin nafion perfluorinated membrane products as determinedby wide- and small-angle X-ray studiesrdquo Journal of PolymerScience Polymer Physics Edition vol 19 no 11 pp 1687ndash17041981
[150] F Binci F Ciarapica and G Giacchetta Natural Gas Dehydra-tion in Offshore Rigs Comparison between Traditional GlycolPlants and Innovative Membrane Systems The University ofNew South Wales School of Chemical Engineering 2003
[151] J Brandrup E Immergut and E Grulke Polymer HandbookJohn Wiley amp Sons 4th edition 1999
[152] M Mulder Basic Principles of Membrane Technology SpringerDordrecht The Netherlands 2nd edition 1996
[153] S M Allen M Fujii V Stannett H B Hopfenberg and J LWilliams ldquoThe barrier properties of polyacrylonitrilerdquo Journalof Membrane Science vol 2 pp 153ndash163 1977
[154] T Watari H Wang K Kuwahara K Tanaka H Kita and K-I Okamoto ldquoWater vapor sorption and diffusion propertiesof sulfonated polyimide membranesrdquo Journal of MembraneScience vol 219 no 1-2 pp 137ndash147 2003
[155] GENERON httpwwwgeneroncom[156] L Wang N Pereira and Y Hung Advanced Air and Noise
Pollution Control Humana Press 2007[157] S Vigneron J Hermia and J Chaouki Characterization and
Control of Odours and VOC in the Process Industries ElsevierScience 1994
[158] V Simmons R Baker J Kaschemekat and J Wijmans Mem-brane Vapor Separation Systems for the Recovery of Halons andCFCs National Institute of Standards and Technology 1992
[159] F I Khan and A Ghoshal ldquoRemoval of volatile organiccompounds from polluted airrdquo Journal of Loss Prevention in theProcess Industries vol 13 no 6 pp 527ndash545 2000
[160] S Dutta Environmental Treatment Technologies for HazardousandMedicalWastes Remedial Scope and Efficacy McGraw-Hill2002
[161] M Place Principles and Practices of Bioslurping Battelle Press2001
[162] B Anderson and Y Imanishi Progress in Pacific PolymerScience Proceedings of the First Pacific Polymer ConferenceMaui Hawaii USA 12ndash15 December 1989 Springer 2012
[163] K Everaert J Degreve and J Baeyens ldquoVOC-air separationsusing gas membranesrdquo Journal of Chemical Technology andBiotechnology vol 78 no 2-3 pp 294ndash297 2003
[164] K Kimmerle C M Bell W Gudernatsch and H ChmielldquoSolvent recovery from airrdquo Journal of Membrane Science vol36 no C pp 477ndash488 1988
[165] H Paul C Philipsen F J Gerner andH Strathmann ldquoRemovalof organic vapors from air by selective membrane permeationrdquoJournal of Membrane Science vol 36 pp 363ndash372 1988
[166] X Feng S Sourirajan H Tezel and T Matsuura ldquoSeparationof organic vapor from air by aromatic polyimide membranesrdquoJournal of Applied Polymer Science vol 43 no 6 pp 1071ndash10791991
[167] C Baukal The John Zink Hamworthy Combustion HandbookVolume 1mdashFundamentals CRC Press 2nd edition 2012
[168] G Paliwal K Agrawal R K Srivastava and S SharmaldquoDomestic liquefied petroleum gas are we using a kitchenbombrdquo Burns vol 40 no 6 pp 1219ndash1224 2014
[169] D Seddon Gas Usage amp Value The Technology and Economicsof Natural Gas Use in the Process Industries PennWell 2006
[170] BMinhas andD Staubs ldquoMembrane process for LPG recoveryrdquo2006
[171] I Pinnau and Z He ldquoPure-and mixed-gas permeation prop-erties of polydimethylsiloxane for hydrocarbonmethane andhydrocarbonhydrogen separationrdquo Journal of Membrane Sci-ence vol 244 no 1-2 pp 227ndash233 2004
International Journal of Polymer Science 19
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
[172] R D Raharjo B D Freeman D R Paul G C Sarti and E SSanders ldquoPure and mixed gas CH4 and n-C4H10 permeabilityand diffusivity in poly(dimethylsiloxane)rdquo Journal ofMembraneScience vol 306 no 1-2 pp 75ndash92 2007
[173] D Roizard E Favre V Teplyakov and V Khotimisky ldquoOrganicmembranes and related molecular separation processes inputin energy and environment areasrdquo in Proceedings of the 3rdFrance-Russia Seminar pp 167ndash170 2007
[174] S Nunes and K-V Peinemann Membrane Technology in theChemical Industry John Wiley amp Sons 2001
[175] T-J Kim I S Bryantseva O B Borisevich et al ldquoSynthesis andpermeability properties of crosslinkable elastomeric poly(vinylallyl dimethylsilane)srdquo Journal of Applied Polymer Science vol96 no 3 pp 927ndash935 2005
[176] A Morisato and I Pinnau ldquoSynthesis and gas permeationproperties of poly(4-methyl-2-pentyne)rdquo Journal of MembraneScience vol 121 no 2 pp 243ndash250 1996
[177] W Lyons and G Plisga Standard Handbook of Petroleum andNatural Gas Engineering Elsevier Science 2011
