(32b) High Purity Hydrogen Generation from Methanol Steam Reforming Using Pd-Based Membrane Reactors | AIChE

(32b) High Purity Hydrogen Generation from Methanol Steam Reforming Using Pd-Based Membrane Reactors


Israni, S. H. - Presenter, University of Houston

Pd membrane based reactors have the potential to generate high purity H2 in a single unit for stationary and mobile applications spanning power stations, soldier-power, and vehicles. Previous studies [1,2] from our group have analyzed in some detail the use of methanol reforming in membrane reactors as a way of intensifying the reaction and separation/purification into a single unit. In the current study methanol steam reforming was carried out using Cu/ZnO/Al2O3 catalyst. The methanol conversion, hydrogen productivity, hydrogen utilization and outlet CO/CO2 ratio for a packed bed reactor (PBR) and a packed bed membrane reactor (PBMR) were compared at different pressures and temperatures. 5 micron thick Pd-Ag ?nanopore' membranes [3] were used in the PBMR. Our previous studies [4,5] have highlighted that slow radial diffusion of hydrogen is one of the major factors limiting productivity & utilization in the membrane reactor. In order to further study this effect we have used membrane reactors with different radial diffusion lengths. The radial diffusion lengths have been varied by changing the reactor diameters while correspondingly changing the ratio of catalyst to inert SiC, to maintain the catalyst volume to membrane surface area ratio constant. A 2 dimensional non-isothermal reactor model has been developed to simulate the results and to elucidate the rate limiting processes. Scale-up principles derived from the experiments and model will be discussed.


1. Harold, M.P., B. Nair, and G. Kolios, ?Hydrogen Generation in a Pd Membrane Fuel Processor: Assessment of Methanol-Based Reaction Systems,? Chemical Engineering Science, 58, 2551-2571 (2003).

2. Lattner, J.R., and M.P. Harold, ?Comparison of Methanol Based Fuel Processors for PEM Fuel Cell Systems,? Appl. Catalysis B. Environmental, 56, 149-169 (2005).

3. Nair, B., and M.P. Harold, ?Pd Encapsulated and Nanopore Hollow Fiber Membranes: Synthesis and Permeation Studies,? J. Membrane Sci., 290, 182-195 (2007).

4. Nair, B., and M.P. Harold, ?Experiments and Modeling of Transport in Composite Pd and Pd/Ag Coated Alumina Hollow Fibers,? J. Membrane Sci., doi:10.1016/j.memsci.2007.11.034 (2008).

5. Israni, S.H., B. Nair and M. P. Harold, ?Hydrogen Generation and Purification in a Composite Pd Hollow Fiber Membrane Reactor: Experiments and Modeling,? Catalysis Today, to appear (2008).