CO2-Selective Water Gas Shift Membrane Reactor for Fuel Cell Hydrogen Processing

In this study, a water gas shift membrane reactor containing both a CO 2 -selective polymeric membrane and a commercial Cu/ZnO/Al 2 O 3 catalyst was developed for hydrogen processing for fuel cells, especially for the proton-exchange membrane fuel cells (PEMFCs). The polymeric CO 2 -selective membrane was synthesized by incorporating fixed and mobile carriers in cross-linked poly(vinyl alcohol). The membrane showed good CO 2 /H 2 and CO 2 /CO selectivities and high CO 2 permeabilities at 110 − 170 °C. In the water gas shift (WGS) membrane reactor, the membrane removed CO 2, one product of the WGS reaction, while the commercial Cu/ZnO/Al 2 O 3 catalyst was used to catalyze the WGS reaction. By removing CO 2 simultaneously, the reversible WGS reaction was shifted toward the products so that the CO concentration was converted and reduced significantly to less than 10 ppm, which met the purity requirement of hydrogen for PEMFCs. A one-dimensional model was used to simulate the reaction and the transport process in a rectangular flat-sheet membrane reactor with well-defined countercurrent gas flows. The modeling results agreed well with the experimental data. A CO concentration of less than 10 ppm and a H 2 concentration of greater than 50% (dry basis) were achieved at various flow rates of a simulated autothermal reformate in the membrane reactor.