Electrochemical hydrogen separation via solid acid membranes

The inorganic proton conductor CsH₂PO₄ (CDP) was investigated as a proton exchange membrane for electrochemical hydrogen separation at temperatures from 230 °C to 250 °C. Carbon-supported Pt and Pd were synthesized via vapor deposition and evaluated as hydrogen oxidation catalysts in hydrogen pump electrodes. The hydrogen oxidation and evolution reactions were reversible on Pt in 100% H₂, and a cell current of 300 mA cm^?2 was produced at a 25 mV overpotential after correction for the membrane ohmic resistance. Anodes were also exposed to hydrogen-containing gas mixtures to simulate reformed fuels. In the case of a stream containing 7% CO (75% H₂, balance CO2), a 300 mA cm^?2 cell current required 45 mV electrode polarization, and in a stream containing 10% CO and 0.25% CH₄ (43% H₂, balance N₂, CO₂), 75 mV polarization was required to obtain the same current. The performance of carbon-supported Pd was virtually identical to that of Pt under each of these conditions.