Hydrogen separation composite membranes

Hou K and Hughes R (2003), Preparation of thin and highly stable Pd/Ag composite membranes and simulative analysis of transfer resistance for hydrogen separation , J Membrane Sci, 214,43-55. 

Palladium-based composite membranes for hydrogen separation in membrane reactors... 

Tanaka D. A. E, Llosa Tanco M. A., Okazaki J, Wakui Y, Mizukami F. and Suzuki T. M., Preparation of pore-fill type Pd-YSZ-Y-Al203 composite membrane supported on a-Al203 tube for hydrogen separation, J. Membrane Sci., 320 (2008) 436 41. 

As an example the use of ceramic membranes for ethane dehydrogenation has been discussed (91). The constmction of a commercial reactor, however, is difficult, and a sweep gas is requited to shift the product composition away from equiUbrium values. The achievable conversion also depends on the permeabihty of the membrane. Figure 7 shows the equiUbrium conversion and the conversion that can be obtained from a membrane reactor by selectively removing 80% of the hydrogen produced. Another way to use membranes is only for separation and not for reaction. In this method, a conventional, multiple, fixed-bed catalytic reactor is used for the dehydrogenation. After each bed, the hydrogen is partially separated using membranes to shift the equihbrium. Since separation is independent of reaction, reaction temperature can be optimized for superior performance. Both concepts have been proven in bench-scale units, but are yet to be demonstrated in commercial reactors. 

The cost of Pd-alloy membranes used for hydrogen separation may be reduced by depositing a thin Pd-alloy film on a suitable porous substrate to form a composite membrane. Almost all of the Pd-alloy membrane development efforts are, thus, focused on preparing thin yet defect-free Pd-alloy composite membranes (e.g., Hopkins, 2007 Coulter, 2007 Delft et al., 2005 Damle et al., 2005 Mardilovich et al., 2002). A detailed review of the Pd-alloy membrane research has been prepared by Paglieri and Way (2002) with an extensive bibliography of the palladium membrane research to date. An updated review has been recently prepared by Collot (2003) and Paglieri (2006). 

Schwartz, M., S. Gade, R. Schaller, and B. Berland, Novel Composite Membranes for Hydrogen Separation in Gasification Processes in Vision 21 Plants, 19th Annual International Pittsburgh Coal Conference, Pittsburgh, PA, September 2002. 

Siriwardane, R.V., J.A. Poston, E.P Fisher, T.H. Lee, S.E. Dorris, and U. Balachandran, Characterization of ceramic-metal composite hydrogen separation membranes consisting of barium oxide, cerium oxide, yttrium oxide, and palladium, Appl. Surf. Sci., 217, 43-49, 2003. 

Uemiya, S., Y. Kude, K. Sugino, N. Sato, T. Matsuda, and E. Kikuchi, A palladium/porous glass composite membrane for hydrogen separation, Chem. Lett., 10,1687-1690,1988. 

Ma, Y., Mardilovich, I.P. and Engwall, E.E. (2003) Thin composite palladium and palladium/alloy membranes for hydrogen separation. Annals of the New York Academy of Sciences, 984, 346—360. 

Because Pd-based metal membranes, commonly used for hydrogen separation [11] are not resistant towards sulphur, not much research has been performed on the use of such membranes in H2S dehydrogenation reactors. Some success has, however, been reported by Edlund and Pledger [12], They developed a platinum-based layered metal membrane that could resist irreversible attack by H2S at 700°C. At this temperature a conversion of 99.4% was achieved in the membrane reactor. Without hydrogen removal the conversion was only 13%. No permeance data is provided, but platinum-based metal membranes are known for their low hydrogen permeance [14], Johnson-Matthey developed palladium composite membranes with a hydrogen permeance of about 1 10 mol/m sPa [14], but these are most probably not resis-... 

Peachey, N. M. Snow, R. C. Dye, R. C. Composite Pd/Ta Metal Membranes for Hydrogen Separation Journal of Membrane Sciences (in press). 

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