(223f) Composite Catalytic Membranes: Enhancing H2 Recovery Membranes by Appropriate Coupling with Water-Gas-Shift Reaction

Membranes for gas purification are a promising alternative to existing cryogenic, absorbtion and pressure-swing adsorption systems. However, permselective membrane materials are often limited by surface inhibition (e.g., CO inhibition of palladium surfaces) or low gas permselectivities (~50:1 for most polymeric membranes). To address these limitations, our research group has developed a composite catalytic-permselective (CCP) membrane design approach, in which a permselective film (e.g., polymeric, metallic) is integrated with a porous catalytic film such that reaction and diffusion within the catalytic layer directly modifies the gas composition at the surface of the underlying permselective barrier [1]. This modification of gas composition has been predicted to enhance permeation rates, membrane permselectivities and reduce surface corrosion/inhibition.

            In this talk, we will review general design rules for implementing this strategy, and demonstrate their extension to the specific application of hydrogen purification from diesel reformate mixtures using water-gas-shift as the enhancing catalytic reaction. Detailed two-dimensional simulations will be presented comparing the resulting CCP design against reference cases of (i) an untreated membrane, and (ii) an untreated membrane employed in a packed-bed membrane reactor configuration. Experimental results for the case of an electroless-plated 30-micron Pd film coupled with water-gas-shift will be presented for comparison with model predictions.  Lastly, a discussion of how this approach may be extended to polymeric systems in order to enhance permselectivity will be presented.

[1] B.A. Wilhite. Composite Catalytic-Permselective Membranes: A Novel Strategy for Enhancing Selectivity and Permeation Rates via Reaction and Diffusion. Ind. Eng. Chem. Res., 2011, 50(17), 10185-10193.