International Journal of Chemical and Biomolecular Science Vol. 1, No. 4, 2015, pp. 244-247 http://www.aiscience.org/journal/ijcbs * Corresponding author E-mail address: [email protected] (F. Farahbod) Investigation of Performance of Sweetening Process of Sour Methane Gas; Novel View Amir Hoseini 1 , Farshad Farahbod 2, * , Abdolhamid Ansari 1 1 Department of Chemical Engineering, Lamerd Branch, Islamic Azad University, Lamerd, Iran 2 Department of Chemical Engineering, Firoozabad Branch, Islamic Azad University, Firoozabad, Iran Abstract Application of nano molybdenum oxide catalyst in gas sweetening is studied, in this work. Experiments are held to evaluate the operating and geometrical parameters in the adsorption process. The quality of process is defined as the ratio of final concentration of H 2 S on the initial concentration of H 2 S. Different values of temperatures, different values of nano particle diameter and also, various values of pressure are emerged on the catalytic bed with 3 cm height and 8 cm diameter. Keywords Proposed Process, Sweetening, Gas, Catalyst, Temperature, Pressure Received: August 12, 2015 / Accepted: September 5, 2015 / Published online: September 25, 2015 @ 2015 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY-NC license. http://creativecommons.org/licenses/by-nc/4.0/ 1. Introduction Desulphurization is a set of technologies used to remove sulphur dioxide ( 2 SO ) sour fuel and from the emissions of other sulphur oxide emitting processes. Methods of removing sulfur dioxide from sour gas and sour oil and furnace exhaust gases have been studied for over 150 years. Early ideas for sour gas, oil and flue gas desulfurization were established in England around 1850 [1]. With the construction of large-scale power plants in England in the 1920s, the problems associated with large volumes of 2 SO from a single site began to concern the public. The 2 SO emissions problem did not receive much attention until 1929, when the House of Lords upheld the claim of a landowner against the Barton Electricity Works of the Manchester Corporation for damages to his land resulting from SO2 emissions. Shortly thereafter, a press campaign was launched against the erection of power plants within the confines of London [1]. This outcry led to the imposition of SO2 controls on all such power plants. The first major desulfurization unit at a utility was installed in 1931 at Battersea Power Station, owned by London Power Company. In 1935, a desulfurization system similar to that installed at Battersea went into service at Swansea Power Station [2]. The third major desulfurization system was installed in 1938 at Fulham Power Station. These three early large-scale desulfurization installations were abandoned during World War II. Large-scale desulfurization units did not reappear at utilities until the 1970s, where most of the installations occurred in the United States and Japan. Desulphurisation of in-situ gas and crude oil is an important process used in a petroleum refinery to reduce the sulphur concentration and production of fuel products such as gasoline, jet fuel, kerosene, diesel and heating oil [3]. So, the resulting fuels meet environmental protection standards. The challenge of fulfilling the world’s growing transportation energy needs is no longer a simple issue of producing enough liquid hydrocarbon fuels [3]. This challenge is instead accentuated by a complex interplay of environmental and operational issues. Environmental issues include societal demands that liquid hydrocarbon fuels be clean and less polluting [4]. The emergence of new refining processes and the increasing use of new forms of energy production, e.g., fuel cells, exemplify operational issues. Together, these trends are driving the need
Transcript
International Journal of Chemical and Biomolecular Science
Molybdenum or Zinc [9]. Molybdenum, known for its high
hydrogenation activities, is preferred as a promoter when
feed stocks containing high amounts of nitrogen and
aromatics need to be processed [10].
It seems, nano particles such as metal oxides can promote the
heating and cooling process [11]. For example, the nano
substances like; metal oxides can enhanced the thermal
stability of some of materials [12].
In this study, molybdenum oxide nano catalyst (spherical and
cylindrical) is used for sweetening process of sour gas. So,
the operating and geometrical parameters are evaluated in
this paper. Therefore, the gained results can be interesting for
related industries and can be applicable in process
optimization.
1.2. Application of Nano Technology for
Sweetening Process
The traditional methods for sweetening process need the
huge amount of energy, So, these methods are not cost
beneficial. The catalysts and nano catalysts can use in
sweetening process and also, enhance the efficiency of these
processes. The nano catalysts are used to sweetening the sour
gas.
2. Materials and Method
All equipment’s are made up of stainless steel since it is non-
corrosive material. Sour methane feed tank contains H2S and
methane gas is used and the flow rate is adjusted by the
valves. After passing a filter an electrical heater the sour gas
stream flows through a compressor.
The gas is compressed and passes through a filter again and
then is fed into the reactor with an adjusted flow rate.
Changing the operating conditions in synthesis of
molybdenum oxide causes different structures of this metal
oxide.
2.1. Preparing Nano-sized MoO2
Molybdenum dioxide (MoO2) is a transition metal oxide that
has long been known to be active for hydrocarbon
decomposition and has more recently shown to display high
reforming activity for various long-chain Hydrocarbons.
Researches showed that MoO2 is highly active for reforming
isooctane via partial oxidation. This process is exothermic
(∆H°= −659.9 kJ/mol) and in the presence of MoO2 proceeds
to full conversion at 700°C and 1 atm. The catalytic activity
shown by MoO2 can be explained in terms of the Mars-van
Krevelen mechanism, which involves the consumption of
nucleo philic oxygen ions provided by the oxygen sub-lattice
with the purpose of sustaining the redox cycles taking place
on the catalyst surface. Despite its interesting catalytic
properties, a very limited number of studies have been
conducted examining the potential of MoO2 as a catalyst for
reforming processes. Such studies were carried out using
commercial MoO2, with particle sizes in the range of a few
micrometres and Brunauer, Emmett, and Teller (BET)
surface areas <10 m2/g. By utilizing nanoparticles we have
shown that it is possible to significantly increase the total
reactive surface area and thus achieve reforming processes
with much higher efficiency levels than those of commercial
MoO2. Nanoparticle MoO2 was synthesized by reduction of
molybdenum trioxide (MoO3) powder in a 1:3 volume ratio
of ethylene glycol to distilled water16. The mixture was
combined in a 45 ml Teflon-lined general-purpose vessel,
which was subsequently sealed and heated to 180°C for 12h.
After cooling, the dark coloured MoO2 was filtered and air
dried at 100°C. Figures 1 and 2 show scanning electron
microscope (SEM) and transmission electron microscope
(TEM) images of nanoparticle MoO2.
Figure 1. The SEM images of synthesized molybdenum oxide nano
particles.
246 Amir Hoseini et al.: Investigation of Performance of Sweetening Process of Sour Methane Gas; Novel View
Figure 2. The TEM images of produced molybdenum oxide nano particles
(cylindrical and spherical).
2.2. Nano Catalysts
The molybdenum dioxide nano particles are used for sulphur
compound removal. These particles have large heat and mass
transfer area. In this state, the C/C0 as process index can
increase, severely.
3. Results and Discussion
Experiments are held to evaluate the effect of process
operation conditions and geometrical conditions of the nano
catalytic bed and also nano particle diameter on the process
performance. The ratio of the H2S final concentration on the
initial concentration of H2S is considered as the creteia of the
performance quality of the sweetening process. Experimental
results are presented in this section and the optimum
conditions which leads to the higher performance quality can
be surveyed by analyzing the curves.
3.1. The Effect of Nano Particle Diameter
The changes in diameter of nano particle affects the amount
of C/C0 as shown in Figure 3 using spherical particle and in
Figure 4 for cylinderical particle. At the optimum pressure 16
bar and temperature of 85 C in the catalytic bed with 8 cm in
diameter and 3 cm height contains spherical nano catalyst the
changes in the amount of C/C0 are investigated in various
particle diameters, 54, 58, 73, 77 and 83 nm. The ratio of the
bed dimeter on the bed height is relatively large and is about
2.67 and assume to provide proper distribution and reaction
surface area avioding channeling. However, changes in
particle diameter shows considerable effect on the amount of
C/C0 for both spherical nad cylinderical nano particles, even
in this provided bed.
Figure 3 and Figure 4 show the higher amount of C/C0 using
larger nanoparticle in diameter. This may relate to the larger
effective surface area provided by the smaller nanoparticle in
the specified geometry of the bed. The smaller particles also
forms thinner gas boundary layer around the particles which
is responsible of convective mass transfer in gas phase.
Smaller particle makes diffusion mass transfer in shorter time
interval. Comparing the results from Figure 3 and Figure 4
illustrates that the spherical and cylinderical type of nano
catalyst with 58 and 77 nm in diameter, obtains lowest
amount of C/C0 of about 0.032 and 0.04, respectively. This
may relates to the proper arrangement of spherical geometery
compares with the cylinderical geometery in the defined
dimensions of catalytic bed.
Figure 3. Performance quality versus the particle diamtere for spherical
catalyst.
Figure 4. Performance quality versus the particle diamtere for cylindrical
catalyst.
3.2. Investigation of Confidence Factor
The C/C0 values are obtaned afte three measurements. So,
the confidence factor percentage for C/C0 as process index is
calculated as 99%. The obtained results illustrate the very
good performance for molybdenum dioxide nano particles as
nano catalysts.
4. Conclusion
The performance quality of nanocatalytic gas sweetening
process is surveyed in this study. The effect of parameters
which are responsible in mass transfer phenomena such as
dimensions of catalytic diameter, diameter of nano catalyst,
shape of nano catalyst and initial driving force are surveyed.
Also, the effect of temperature and pressure on the amount of
process quality is considered in this work. The main
International Journal of Chemical and Biomolecular Science Vol. 1, No. 4, 2015, pp. 244-247 247
experimental results are presented as follows:
1. The optimum pressure and temperature for both type of
spherical and cylinderical is 16 bar and 85 C. Although the
obtained amount of C/C0 for spherical type is 0.054 and
lower than that is obtained (0.061) using cylinderical type
with the same diameter of 77 nm.
2. The optimum value of catalyst diameter of spherical type
is 58 nm and for cylinderical tyoe is 77 nm which introduces
the values of 0.032 and 0.04 for C/C0, respectively.
References
[1] Yuxiao Niu, Mingyang Xing, Baozhu Tian, Jinlong Zhang, 2012, “Improving the visible light photocatalytic activity of nano-sized titanium dioxide via the synergistic effects between sulfur doping and sulfation,’’ Applied Catalysis B: Environmen, 115–116 (5) pp. 253-260.
[2] Rao Mumin, Song Xiangyun, Cairns Elton J., 2012, ‘’Nano-carbon/sulfur composite cathode materials with carbon nanofiber as electrical conductor for advanced secondary lithium/sulfur cells,’’ J. Power Source., 205 (1), pp. 474-478.
[3] Zhang Yongguang, Zhao Yan, Konarov Aishuak, Gosselink Denise, Soboleski Hayden Greentree, Chen P., 2013, “A novel nano-sulfur/polypyrrole/graphene nanocomposite cathode with a dual-layered structure for lithium rechargeable batteries,’’ J. Power Source. 241 (1), pp. 517-521.
[4] Hosseinkhani M., Montazer M., Eskandarnejad S., Rahimi M.K., 2012, “Simultaneous in situ synthesis of nano silver and wool fiber fineness enhancement using sulphur based reducing agents, ’’Colloids and Surfaces A: Physicochem. Eng. Aspect, 415 (5), pp. 431-438.
[5] Christoforidis Konstantinos C., Figueroa Santiago J.A.,
Fernández-García Marcos, 2012, “Iron–sulfur codoped TiO2 anatase nano-materials: UV and sunlight activity for toluene degradation,’’ Applied Catalysis B: Environment, 117–118 (18), pp. 310-316.
[6] Balouria Vishal, Kumar Arvind, Samanta S., Singh A., Debnath A.K., Mahajan Aman, Bedi R.K., Aswal D.K., Gupta S.K., 2013, "Nano-crystalline Fe2O3 thin films for ppm level detection of H2S,’’ Sensors Actuators B: Chemical, 181, pp. 471-478.
[7] Habibi R., Rashidi A. M., Towfighi Daryan J., Alizadeh A., 2010,"study of the rod – like and spherical nano ZnO morphology on H2S removal from natural gas". Appl. Surf. Sci., 257, pp. 434- 439.
[8] Novochimskii II., Song CH., Ma X., Liu X., Shore L., Lampert J., Farrauto R. J., 2004, "Low temperature H2S removal from steam containing gas mixtures with ZnO for fuel cell application. 1. ZnO particles and extrudates". Ene. Fuel, 18, pp. 576-583.
[9] Habibi R., Towfighi Daryan J., Rashidi A.M., 2009, Shape and size-controlled fabrication of ZnO nanostructures using noveltemplates, J. Exp. Nanosci. 4 (1) 35-45.
[10] Gautam Das, Bir Sain, Sunil Kumar, 2012, Synthesis, characterization and catalytic activity of cobalt phthalocyanine dichloride in sweetening of heavier petroleum fractions, Catalysis Today, 198 (1), 228-232.
[11] Durán-Moreno A., García-González S.A., Gutiérrez-Lara M.R., Rigas F., Ramírez Zamor R.M., 2011, Assessment of Fenton's reagent and ozonation as pre-treatments for increasing the biodegradability of aqueous diethanolamine solutions from an oil refinery gas sweetening process, Journal of Hazardous Materials, 186 (2-3), 1652-1659.
[12] Ganguly Sudip K., Das Gautam, Kumar Sunil, Sain Bir, Garg Madhukar O., 2012, Mechanistic kinetics of catalytic oxidation of 1-butanethiol in light oil sweetening, Catalysis Today, 198 (1), 246-251.
