279861 CO2-Selective Membranes for H2 Purification for Fuel Cells

Thursday, November 1, 2012: 9:01 AM
402 (Convention Center )
Lin Zhao1, Kartik Ramasubramanian1, Yanyan Zhao2 and Winston Ho3, (1)William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, (2)China Agricultural University, Beijing, China, (3)Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH

This presentation covers an experimental and modeling study of carbon dioxide-selective membranes for hydrogen purification for fuel cells.  We have synthesized CO2-selective membranes by incorporating amino groups into polymer networks.  The membranes have shown high CO2 permeability and selectivity vs. hydrogen, carbon monoxide and nitrogen up to 180oC.  We have elucidated the effect of amine steric hindrance in the solid membrane, showing significant enhancement for CO2 transport.  Hydrogen sulfide permeates through the membrane much faster than CO2, allowing H2S removal in the treated synthesis gas before water-gas-shift (WGS) reaction.  Our initial experiments have shown a nearly complete removal of H2S from 50 ppm in synthesis gas to about 10 ppb in the hydrogen product. 

In the modeling of the WGS membrane reactor in a spiral-wound membrane module based on both mass and enthalpy balances, the kinetics of the WGS reaction was incorporated using a published rate expression for the commercial CuO/ZnO/Al2O3 catalyst.  The resulting 1-D (countercurrent flow of feed and sweep streams) or 2-D (crossflow) system of differential equations were solved using COMSOL Multiphysics.  The model was validated by comparing the predicted CO results with previously published experimental data for a lab-scale flat rectangular membrane reactor, achieving <10 ppm carbon monoxide in the hydrogen product.  The effects of operating parameters like feed pressure, sweep to feed flow rate ratio and steam/CO ratio on membrane area and hydrogen recovery were carried out for reaching <10 ppm carbon monoxide in the hydrogen product.  Results show that although the countercurrent flow mode is the most efficient in terms of CO reduction; however, the crossflow mode might provide a better trade-off between CO reduction and heat management.

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See more of this Session: Fuel Cell Membranes - I
See more of this Group/Topical: Separations Division