Electrochemical Hydrogen Separation via the Solid Acid Electrolyte Cesium Dihydrogen Phosphate

Abundant, inexpensive, high purity molecular hydrogen as a medium for energy distribution is potentially enabling for adoption of alternative electricity generation schemes. Steam reforming of natural gas remains the dominant method of producing large amounts of hydrogen. However, this process also creates by-products, most notably, carbon monoxide and carbon dioxide. Separation to ultra-high purity hydrogen from these syngas reformate streams by traditional methods, such as pressure swing absorption, has its disadvantages including long cycle times, contamination and a large equipment footprint. Alternative methods of hydrogen separation, such as electrochemical pumping, are a viable alternative to this separation dilemma due to their relative simplicity and potential efficiency.

The solid-state proton conductor cesium dihydrogen phosphate has shown potential in electrochemical hydrogen separation devices operating on reformed hydrocarbons. In this work, we have synthesized a suite of nanoparticles, including Pt, Pd, Ru, Ni and Cu, supported on carbon for implementation in solid acid electrodes. We evaluate these materials at an intermediate temperature of 250 degrees Celsius for the hydrogen oxidation and reduction reaction, as well the electrooxidation of carbon monoxide. Functionally graded anodes are fabricated to balance CO conversion activity with hydrogen oxidation. These re-engineered anodes are implemented in conjunction with Ni-based cathodes to demonstrate efficient hydrogen separation using ultra low loadings of Pt from syngas-like inputs.