Water gas shift membrane reactors separation

Basile, A., Chiappetta, G., Tosti, S., Violante, V. (2001). Experimental and simulation of both Pd and Pd/Ag for a water gas shift membrane reactor. Separation and Purification Technology, 25, 549—571. 

It has been shovm that membranes can enhance the conversion of a water-gas shift membrane reactor and concurrently separate hydrogen from carbon dioxide. The efficiency of CO2 control using the membrane reactor with a H2/CO2 selectivity of 15 is significantly higher compared to a conventioncd technique (i.e. wet washing with a sorbent). It is not necessary to exceed a selectivity of approximately 40 for H2/CO2 for the process under consideration, because further increase in reactor performance seems marginal. Enlargement of the permeation is an important aspect on the other hand, so that the total surface area necessary for the full-scale application can be reduced. 

Furthermore, the application of the SOD membrane in a FT reaction has been investigated. The advantages of water removal in a FT reaction are threefold (i) reduction of H20-promoted catalyst deactivation, (ii) increased reactor productivity, and (iii) displaced water gas shift (WGS) equilibrium to enhance the conversion of CO2 to hydrocarbons [53]. Khajavi etal. report a mixture of H2O/H2 separation factors 10000 and water fluxes of 2.3 kg m h under... 

Liu, P.K.T., Carbon Molecular Sieve Membrane as Reactor/Separator for Water-Gas-Shift Reaction, Proceedings of2007 U.S. DOE Hydrogen Annual Merit Review Meeting, Arlington, VA, May 2007. 

Pex, P.P.A.C. and Y.C. van Delft, Silica membranes for hydrogen fuel production by membrane water gas shift reaction and development of a mathematical model for a membrane reactor, in Carbon Dioxide Capture for Storage in Deep Geologic Formations—Results from the C02 Capture Project Capture and Separation of Carbon Dioxide from Combustion Sources, eds., D. Thomas, and B. Sally, Vol. 1, Chapter 17, 2005. 

This system includes several mixing and heat exchange units. A concept for an integrated, microtechnology-based fuel processor was proposed by PNNF [8]. As examples for unit operations which may be included in future integrated systems the same publication mentions reactors for steam reforming and/or partial oxidation, water-gas shift reactors and preferential oxidation reactors for carbon monoxide conversions, heat exchangers, membranes or other separation components. 

Basile, A. Criscuoli, A. Santella, F. Drioli, E. Membrane Reactor for Water Gas Shift Reaction Gas Separation and Purification 10(4) (1996a) 243-254. 

Giessler, S., Jordan, L., Diniz da Costa, J.C., and Lu, G.Q. Performance of hydrophobic and hydrophilic silica membrane reactors for the water gas shift reaction. Separation and Purification Technology, 2003, 32, 255. 

A schematic of a PBMR, in this case for the water-gas shift reaction, is given in Fig. 14.2. Of course the catalytic reactor and the membrane unit can also be separated from each other, but can still be used to enhance the yield of a catalytic process, as will be shown in Section 14.3 (see also Fig. 14.5). 

In this section some examples of inorganic gas separation membranes in membrane reactor applications will be discussed. A first indication of the technical and economic feasibility of these membranes in dehydrogenation reactions and in the water-gas shift reaction will be given. 

NETL has been actively investigating through both experimental and computational studies the potential of Pd-Cu alloys because of their potential applicability for gasifier and post-gasifier water-gas shift (WGS) membrane reactors and similar harsh environment hydrogen separation applications. Recent computational studies by Sholl and Alfonso have focused on the prediction of alloy membrane permeability values and the interaction of S with potential membrane materials . Our experimental studies on the permeability of a series Pd-Cu alloys in pure hydrogen and in the presence of H2S have also been recently reported . 

Antoniazzi AB, Haasz AA, Auciello O, Stangeby PC. Atomic, ionic and molecular hydrogen permeation facihty with in situ auger surface analysis. J Nucl Mater. 1984 670 128-9. BasUe A, Ciiscuoli A, Santella F, Diioli E. Membrane reactor for water gas shift reaction. Gas Separation Purification. 1999 10(4) 243-254. 

A possible approach Natural gas can be converted at a high temperature into hydrogen, CO, C02 (syngas) in a steam reformer or partial-oxidation reactor, or autothermal reformer which is a combination of the first two. Most of the CO in the syngas is typically converted into carbon dioxide at a lower temperature in a water-gas shift reactor. The remaining small amount of CO must be removed to below 10 ppm level. This can be done using adsorption, or membrane separation, or catalytic preferential oxidation (at about 90°C with an air stream), or other practical means. Also, there are designs with membrane reformers in the literature. 

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