(386g) Design of Composite Catalytic Membrane for Permselective Hydrogen Extraction From Ethanol

Conventional membrane systems for high purity hydrogen production from hydrocarbons typically employ permselective Pd or Pd-alloy materials in conjunction with hydrocarbon reforming.  Palladium is expensive, prone to poisoning by carbonaceous materials and suffers embrittlement over multiple thermal cycles. In the light of these challenges our research group is exploring the use of catalytic membranes to achieve hydrogen separation without relying upon costly and delicate permselective materials.

In this presentation we develop a detailed model of a multilayer catalytic membrane for achieving selective hydrogen extraction solely by manipulating diffusion and reaction across the non-permselective catalytic membrane.  The influence of pore diameter and membrane thickness simulation results of single-layer designs predicts that H₂: CO permselectivities up to 50:1 can be achieved solely by reaction and diffusion by appropriate selection of membrane. The influence of ethanol concentration, steam concentration and steam split between feed/sweep streams is also reported. Results indicate the need for a sufficient diffusional resistance within the membrane for allowing reaction to impart H₂: CO permselectivity. Simulation results show that membrane selectivities in excess of 1000:1 can be achieved using multi-layer composite catalytic membranes.