This presentation should be cited as: Adewole (2012) Referenced as:Jimoh K. Adewole (2012), Opportunities for Membrane Separation in Enhanced Oil Recovery, KFUPM Research Institute Technical Seminar Series 2011 –2012, Delivered on May 21st, 2012.
OPPORTUNITIES FOR MEMBRANE SEPARATION
IN ENHANCED OIL RECOVERY
BYADEWOLE Jimoh K.
Center for Petroleum & Minerals, Research InstituteKing Fahd University of Petroleum and Minerals
Dhahran, Saudi Arabia
OutlinesNeeds for Research in Membrane TechnologyEnhanced Oil RecoveryMembrane Separation TechnologySome Success Stories of MGSChallenges in Membrane Material Development for Gas SeparationSome BreakthroughsResearch Areas of ExplorationsConcluding RemarksAcknowledgementReferences
Tuesday, May 22, 2012 3Adewole J. K., CPM-KFUPM
4
0
20
40
60
80
100
120
140
0 5000 10000 15000 20000 25000 30000 35000 40000 45000GDP / Capita (US$)
Ene
rgy
Con
sum
ptio
n (‘0
00 K
WH
r / C
apita
)
Energy Consumption per Capita vs. GDP per Capita (Ghosh, 2008)
Ukraine
Russia
US
Kazakhstan Czech Republic
Malaysia
TurkeyBrazil
RomaniaThailandChina Egypt PhilippinesIndonesia
India
Italy
FranceGermany
UKJapan
Canada
80% of Global Population
NEEDS FOR RESEARCH IN MS
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World Population
Year 2007 = 6.7billions
Developed Countries = 1.2
billions
Year 2050 = 9.2 billion
Year 2050; Asia = 5.3 billion
World Energy Demand
Energy Increase (UBE)= 7.7
Asia Growing Econs
Asia Visions to join More
Developed Countries
Energy Increase (CE) = 5.5
World Energy Scenario in 2050 (Koros et al., 2009)
NEEDS FOR RESEARCH IN MS
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2050
To be Effective
Membrane must be Introduced prior to Energy inefficient thermally intensive process.
5x increase in global commodities ≈ 66% increase in current energy consumption
Industrial Separation
Industrial Sector Consumes 33% Total Energy ConsumptionSeparation Process Consumes 40% Industrial Energy NeedsEquivalent to 13.2% of total Energy Consumption
Valuable savings
Achieved using available gas separation membranes units while
aggressively pursuing development of more novel materials
NEEDS FOR RESEARCH IN MSIndustrial Energy Consumption in 2050 (Koros et al., 2009)
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Suspended Particles and Macromolecular Solutes ProcessingFlash Evaporation 73kwh/m3
MF/UF 7.6Kwh/m3
Thermal Distillation Plant 78.5Kwh/m3
State-of-the-art Seawater RO 6.7Kwh/m3
Cryogenic Distillation 0.302Kwh/lb propylene prod
50millions gallons/day Seawater Processing
Propylene/Propane Separation
Vapor Permeation Membrane 0.050Kwh/lb propylene prodSources: Koros et al., (2009); Humphrey & Keller (1997); Eykamp (1997); Blume (2004); Gottschlich & Jacobs (1998); Collings et al. (2004)
NEEDS FOR RESEARCH IN MS
7
Adewole J. K., CPM-KFUPM
Economic Comparison: Dew point ControlPropane Refrigeration 0.165 $/inlet Mscf
Membrane 0.098 $/inlet Mscf
Sources: Private Study by Purvin and Gertz, June 1999, MTR, USA
NEEDS FOR RESEARCH IN MS
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Enhanced Oil Recovery
EOR METHODS
Other/Unconventional
Thermal EOR
Chemical EOR
Classifications (Al-Mjeni et al., 2011)
(Most Common Classification from
Literature)
Solvent/Miscible
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CO2-EOR ?
Miscible Fluid Displacement
Global Warming
Available CO2 Pipeline
Cheap Sources of CO2
(Environment)
(Transportation)
(Availability)
(Rooted in the early Stages of Industrial Revolution)
Level of Toxicity
(Gas Properties)
Enhanced Oil Recovery
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Partial separation of a mixture of two or morecomponents by use of a semi-permeable barrier
Figure: Basic Membrane Separation
Membrane Separation Technology
Driving Forces:Hydrostatic Pressure
Concentration
Electrical Potential
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Semi-Permeable Barrier
Membrane
Organic
Glassy Rubbery
Inorganic/ Carbon Liquid
Hybrid Membrane (Provide Property and Processing Advantages)
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Organic Membrane Separation
Figure: Motion of molecules with the polymer cavities (Xiao et al., 2009)
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Glassy & Rubbery Polymers
14
Glassy MembranesFast Gas Slow Gas
HexanePropaneH2O
Ethane
CO2
MethaneHydrogen
Nitrogen
HydrogenCO2H2O
Nitrogen
MethaneEthane
PropaneHexane
Rubbery Membranes Fast Gas Slow Gas
Source: MTR Inc., USA
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P1 D1 . S1
P2 D2 . S2
=
Permeability = Diffusivity * Solubility (P) (D) (S)
Membrane Selectivity
Solution-Diffusion Mechanism
Adsorption at high pressure side
Diffusion through the membrane
Desorption at low pressure side
Membrane Selectivity; Measure of Separation Performance
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Module housing
SpacerMembraneSpacer
Feed flow
Permeate flow after passing through membrane
Feed flow
Feed flowPermeate flow
Residue flow
Residue flow
Membrane Modules
Spiral Wound Membrane ModuleHollow Fiber
Source: MTR Inc, Aquilo Gas Separation
Cross Section representation
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Advantages of Membrane Separation
• Offshore production platform applications
• Minimal or no operator attention
• Small footprint, low weight
• Low maintenance
• Lower capital and operating costs
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Types Possible EOR Application
Reverse Osmosis /Hyper filtration
Miscible Gas, Smart Water, Thermal
Nano filtration Smart Water, Thermal, Microbial
Ultra filtration/ Micro filtration Chemical, Thermal
Types of Membrane Separation
Membrane Distillation Gas Enrichment Unit for Miscible Gas flooding
Gas Separation Gas Enrichment Unit for Miscible Gas flooding
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Some Success Stories of MGS
Plant Initial Cap
(MMscfd)
Expanded Cap(MMscfd)
Pressure
(bar)CO2 Mole% Year of
Comm
Kelly-Snyder Field 70 600 N/A 87 2006CakerawalaProduction Platform
N/A 700 N/A 37
Qadirpur, Pakistan 265 500 59 6.5 1999Taiwan 30 ─ 42 ─ 1999Kadanwari, Pakistan 210 ─ 90 ─ N/AEOR facility, Mexico 120 ─ N/A 70 N/ASlalm & Tarek, Egypt 100 ─ 65 N/ATexas, USA 30 ─ 42 30 N/ASource: Koros et al., (2009); and Engelien, (2004); Dortmundt, UOP, (1999)
Membrane Gas Separation Plants
Adewole J. K., CPM-KFUPM
Figure: Enhanced Oil Recovery System in Mexico (UoP)
Commissioned July 1997120 MMSCFD inlet gas 70% CO2. Outlet gas 93% CO2 and is reinjected.
EOR Gas Enrichment Unit
Some Success Stories of MGS
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Customized EOR GE Unit: Membrane for CO2 Removal From Reformer Gas by MTR Inc, USA
Some Success Stories of MGSEOR Gas Enrichment Unit
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Challenges in Material Development for Polymeric MGS
Low Productivity
Balanced Permeability & Selectivity
Physical Aging
Plasticization &Conditioning
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The first challengeGas Transport through membrane began 1950 Emergence of High Flux asymmetric Loeb-Sourirajan membranes –
selective top thin layer (0.1micron) and porous support in 1980Could not be used for GS due to surface defectSolved using thin layer of silicone rubber coating
Low Productivity
Membrane Permeability Selectivity (CO2/CH4)
Celuose Acetate 8.9 20-25
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Permeability and Permselectivity for pure gases at feed pressure of 3.5 bar; membrane thickness of 20 μm (Bernardo et al., 2009)
Commercial Membranes with High CO2 Permeability have Emerged
Low Productivity
0
100
200
300
400
500
600
Cellulose Accetae
Cytop Hyflon AD 60
Hyflon AD 80
Teflon AF 1600
Per
mea
bilit
y (b
arre
r)
05
101520253035404550
Cellulose Accetae
Cytop Hyflon AD 60
Hyflon AD 80
Teflon AF 1600
Per
mse
lect
ivit
y
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Robeson (1991) Upper Bound Curves Discovered with an Empirical Correlation to Represent a General Trade-Off
Figure: Trade-off for CO2/CH4 gas pair in DABA containing polyimides
Better Balance of Selectivity & Permeability
Materials that do notobey the simple rules areneeded to achieve higherselectivity/permeabilitycombination
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Robeson’s Upper Bound Curves was further studied and
modified by Freeman (1999).
Discovered that to surpass the upper bound emphasis should be
placed on increasing the selectivity by:
Inter-chain spacing
Chain stiffness
Better Balance of Selectivity & Permeability
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Robeson’s Empirical Model Revisited with more data in 2008
Figure: Robeson's trade-off for CO2/CH4 gas pair polyimides
Better Balanced of Selectivity & Permeability
17 years later few membranes are above the 1991 Robeson’s Upper Bound Limit
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Recent Report on Surpassing of Upper Bound Limit
Better Balanced of Selectivity & Permeability
Figure: Robeson's trade-off for CO2/CH4 gas pair for microporous Thermally Rearranged polybenzimidazole (TR-PBI) membrane heat treated at 450oC (Han et al., 2010).
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Pressure dependent phenomena Caused by the dissolution of certain penetrants within the polymer matrix Disruption of the chain packing and enhance inter-segmental mobility of
polymer chains (Xiao et al., 2009 ). Induced by condensable gases and vapours encountered in gas
separation involving aggressive feed streams, such as CO2 in natural gas (Qiu et al., 2011 and Wind et al, 2004).
Causes an increase in permeability and a decrease in selectivity as the partial pressure of plasticizing penetrant rises beyond a critical level.
Plasticization and Conditioning
Plasticization ?
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Plasticization and ConditioningInfluence of upstream pressure on permeability coefficients(a) Low-sorbing gases(b) Plasticization of a rubbery polymer (c) dual-mode behavior in a glassy polymer (d) dual-mode behavior at low pressure (<10 atm) and plasticization at higher pressure
Matteucci et al. (2006)
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Pressure at which the permeability starts to increase with increasing pressure. Pressure at which gas permeability exhibits a minimum value (Xiao et al.,
2009; and Scholes et al., 2010)
Plasticization and Conditioning
Plasticization Pressure
Decline in membrane performance Increase in methane loss Decline in process reliability (Wind, 2004)
Effects of Plasticization
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Sorbing sizeable quantities of penetrant into glassy polymer Glassy state is altered Polymers do not return to their original state after removal of the
penetrant (Murphy et al., 2009)
Plasticization and Conditioning
Conditioning in Glassy Polymer
EffectsPermanent changes to the morphology and transport properties of
membrane due to irreversible volume dilation (Xiao et al., 2009 )Gas separation performance becomes time-dependentAffect the reliability of this performance and hinder commercialization of
membrane for industrial separation (Xiao et al. 2009)
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Flow CapacityMax: 8 MMSCFD Operated: 2.5-3.0 MMSCFD Pressure ratingMax: 1250 psig Operated: 475 psig TemperatureMax: 135oF Operated: 100-125oF
Plasticization and Conditioning
Membrane Material research Inc, USA
Industrial Example
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Physical Aging due to nonequilibrium state of glassy polymers
Diffusion of FreeVolume and latticecontraction (physicalAging) (Xiao et al.,2009)
Physical Aging
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Some BreakthroughsSuggested Methods for Improved Separation Performance
Crosslinking and Thermal Treatment (Qiu et al., 2011; & Kanehashi, et al.,2010)
•Decarboxylation-induced thermal cross linking•Cross-linking by diamino compounds at ambient temperature•Monoesterification & transesterification reaction of carboxylic acid•Imide ring opening reactions•Diols-alder type cyclization reactions
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Some BreakthroughsSuggested Methods for Improved Separation PerformanceCopolymerization (Xiao et al., 2009)Template Polymerization & Use of Porogens (Askari et al., 2012 ) Thermal Rearrangement (Park et al., 2010; Park et al.,2007; Tullos
et al., 1999)Polymer Blending (Xiao et al., 2009)Mixed Matrix (Adewole et al., 2011; Koros et al., 2009; and Chung
et al., 2007)Grafting of Polymer Backbone (Pixton & Paul,1995; and Scholes et
al., 2010)Dual-layer hollow fiber spinning process (Hosseini et al., 2010)
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Some Breakthroughs
120oC, 24hr 180oC, 24hr 300oC, 20hr
330oC, 20hr 350oC, 1hr 370oC, 1hr
150 140190
290330
450
14 45 48 48 48 48
Separation Performance of Decarboxylation-induced Thermal Crosslinking of Hollow Fiber 6FDA-DAM:DABA (3:2) Membrane for
Pure CO2 Gas (Qiu et al., 2011)
Permeability PermSelectivity Plasticization Pressure(barrer) (bar)
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Some Breakthroughs
180oC, 24hr 330oC, 20hr 350oC, 1hr
100
250
300
37.5 30 27.569 69 55
Separation Performance of Decarboxylation-induced Thermal Crosslinking of Hollow Fiber 6FDA-DAM:DABA (3:2) Membrane for
10%CO2 /90% CH4Gas (Qiu et al., 2011)
Permeability PermSelectivity Plasticization Pressure(barrer) (bar)
180oC, 24hr 330oC, 20hr 350oC, 1hr
130
250 265
27 27 2655 69 69
Separation Performance of Decarboxylation-induced Thermal Crosslinking of Hollow Fiber 6FDA-DAM:DABA (3:2) Membrane for
50%CO2 /50% CH4Gas (Qiu et al., 2011)
Permeability PermSelectivity Plasticization Pressure(barrer) (bar)
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
0
10
20
30
40
50
60
Crosslinked with Ethylene glycol in
DMAc
Decarboxylation at high Temperature
+220 oC, 23hr
Decarboxylation at high Temperature+220 oC, 23hr + rapid Quenching from above Tg
Plas
ticiza
tion P
ressu
re (b
ar)
Improved Antiplasticization Resistance via Crosslinking of 6FDA-DAM-DABA (2:1) (Staudt-Bickel & Koros ,1999; and
Kratochvil & Koros, 2008)
39
Some Breakthroughs
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Some Breakthrough
2
2.5
3
3.5
4
4.5
Mixed CH4/CO2
PureHDPE
1wt%C15A
5wt%N1.44P
Perm
eabilit
y (ba
rrer)
Mixed Matrix Polyethylene/Nanoclay for Natural Gas Tranportation at 50oC and 100bar (Adewole et al., 2012)
CO2 Transport Pipeline
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Some Breakthroughs
Schematic of various gas transport routes through hybrid polymeric membranes (Xiao et al., 2009)
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
Research Areas for ExplorationDevelopment of optimum membrane configuration for
available gas separation membranesAggressive research efforts towards developing more novel
materials with better balanced of selectivity and flux, and resistance to plasticization, conditioning and aging
Evaluation of the best source of CO2 for EOR GE unitLiquid membranes from renewable sources (date seed oil)Development of methods where membranes are fabricated at
lower temperature is neededDevelopment of novel large scale membrane spinning
processes for mixed matrix (hybrid)42Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
43
Compact enough to be driven by solar power
Light
Photosynthesis
Fuels Electricity
Photovoltaic
MFeed Retentate
Permeate
Membrane module
Research Areas for Exploration
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
Concluding Remarks
44
Multidisciplinary research efforts is essential
Academic-Industry collaborative research is vital
Valuable Savings can be achieved using available materials while
aggressively pursuing development of more novel materials
Developing countries such as should incorporate membrane units from
the beginning. Thermally intensive units have 30-50 years useful lives
Suggested methods should be extended to polymers that are currently
useful for gas separation in the industry
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
Acknowledgement
45
CPM, RI and KFUPM
Director CPM, Dr A. S. Sultan
Dr L. O. Babalola
KACST and Ministry of Petroleum & Mineral
Resources
Friends and ColleaguesTuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
46
Adewole, J. K., Jensen, L., Al-Mubaiyedh, U. A., von Solms, N., & Hussein, I. A. (2011). TransportProperties of Natural Gas through Polyethylene Nanocomposites. Journal of PolymerResearch
Al-Mjeni, R., Arora, S., Cherukupalli, P., Wunnik, J., dwards, J., Febler, B. J., et al. (2011). Has the TimeCome for EOR? Oilfield Review , 22 (4), 16-34.
Partha S. Ghosh & Associates, (2008). Presntation on How Chemical Engineering will Drive the 21stCentury: The Mega Possibilities Ahead.
Bernardo, P., Drioli, E., & Golemme, G. (2009). Membrane Gas Separation: A Review/State of the Art.Ind. Eng. Chem. Res. , 48, 4638–4663.
Blume, I. (2004). Norit Ultrafiltration as Pretreatment for RO for Wastewater Reuse: The SulaibiyaProject. Presentation at Advanced Membrane Technology II Conference, . Irsee, Germany.
Collings, C. W., Huff, G. A., & Bartels, J. V. (2004). Patent No. Pat. Appl. Publ. 20040004040 A1. USA.Dortmund, D., Doshi, K., ‘Recent Developments in CO2 Removal Membrane Technology,Eykamp, W. (1997). Membrane Separation Processes. In Perry's Chemical Engineers' Handbook (7th
ed., p. Chapter 22). New York, NY: Mc Graw-Hill.Gertz, P. a. (1999, June ). Propane Refrigeration Cost. Private Study .Gottschlich, D., & Jacobs, M. L. (n.d.). Monomer Recovery Process, Membrane Technology and
Research Inc., USA, p. 14.http://www.uop.com/gasprocessing/TechPapers/CO2RemovalMembrane.pdfHumphrey, J. L., & Keller, G. E. (1997). Energy Considerations, in Separation Process Technology. New
York, NY: Mc Graw-Hill.
References
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
47
Jacobs, K. A. (n.d.). New Membrane Applications in Gas Processing. Membrane Technology andResearch, Inc.
Kanehashi, S., Sato, S., & Nagai, K. (2010). Synthesis and Gas Permeability of Hyperbranched andCross - linked Polyimide Membranes. In Y. Yampolskii, & B. Freeman (Eds.), Membrane GasSeparation (pp. 3-27). John Wiley & Sons, Ltd.
Koros, W. K., Krotochvil, A., Shu, S., & Husain, S. (2009). Energy and Environmental Issues and Impactsof Membranes in Industry. In E. Drioli, & L. Giorno (Eds.), Membrane Operations InnovativeSeparations and Transformations (pp. 139-165). Weinheim: Wiley-VCH Verlag GmbH & Co.KGaA.
Kratochvil, A. M., & Koros, W. J. (2008). Decarboxylation-Induced Cross-Linking of a Polyimide forEnhanced CO2 Plasticization Resystance. Macromolecules , 41, 7920- 7927.
Matteucci, S., Yampolskii, Y., Freeman, B. D., & Pinnau, I. (2006). Transport of Gases and Vapors inGlassy and Rubbery Polymers. In Y. Yampolskii, I. Pinnau, & B. D. Freeman (Eds.), MaterialsScience of Membranes for Gas and Vapor Separation (pp. 1-40). John Wiley & Sons, Ltd.
Murphy, T. M., Offord, G. T., & Paul, D. R. (2009). Fundamentals of Membrane Gas Separation. In E.Drioli, & L. Giorno (Eds.), Membrane Operations. Innovative Separations and Transformations(pp. 63-82). Weinheim: WILEY-VCH Verlag GmbH & Co. KGaA.
Park, H. B., Han, S. H., Jung, C. H., Lee, Y. M., & Hill, A. J. (2010). Thermally rearranged (TR) polymermembranes for CO2 separation. Journal of Membrane Science , 359 , 11–24.
Park, H. B., Jung, C. H., Lee, Y. M., Hill, A. J., Pas, S. J., Mudie, S. T., et al. (2007). Polymers with cavitiestuned for fast selective transport of small molecules and ions,. Science , 318, 254–258.
References
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
48
Paul, D., & Robeson, L. (2008). Polymer nanotechnology: Nanocomposites. Polymer , 49 , 3187–3204.Pixton, M. R., & Paul, D. R. (1995). Gas transport properties of adamantane- based polysulfones.
POLYMER , 36 (16), 3165.Qiu, W., Chen, C.-C., Xu, L., Cui, L., Paul, D. R., & Koros, W. (2011). Sub-Tg Cross-Linking of a Polyimide
Membrane for Enhanced CO2 Plasticization Resistance for Natural Gas Separation.Macromolecules , 44, 6046–6056.
Scholes, C. A., Chen, G. Q., Stevens, G., & Kentish, S. E. (2010). Plasticization of ultra-thin polysulfonemembranes by carbon dioxide. Journal of Membrane Science , 346 , 208–214.
Staudt-Bickel, C., & Koros, W. J. (1999). Improvement of CO2/CH4 separation characteristics of polyimidesby chemical crosslinking. Journal of Membrane Science , 155, 145–154.
Tullos, G., Powers, J., Jeskey, S., & Mathias, L. (1999 ). Thermal conversion of hydroxycontaining imides tobenzoxazoles: polymer and model compound study. Macromolecules , 32 , 3598–3612.
Wellington, J. M., & Ku, A. Y. (2011). Opportunities for Membranes in Sustainable Energy. Journal ofMembrane Science , 373, 1-4.
Wind, J. D., Paul, D. R., & Koros, W. J. (2004 ). Natural gas permeation in polyimide membranes. Journal ofMembrane Science , 228 , 227–236.
Xiao, Y., Low, B. T., Hosseini, S. S., Chung, T. S., & Paul, D. R. (2009 ). The strategies of moleculararchitecture and modification of polyimide-based membranes for CO2 removal from natural gas -A review. Progress in Polymer Science , 34 , 561–580.
References
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Thank YouFor
ListeningTuesday, May 22, 2012 Adewole J. K., CPM-KFUPM
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Comments &
Contributions
Tuesday, May 22, 2012 Adewole J. K., CPM-KFUPM