CARBON-MONOXIDE REMOVAL FROM HYDROGEN-RICH FUEL-CELL FEEDSTREAMS BY SELECTIVE CATALYTIC-OXIDATION

Indirect methanol fuel cells currently being investigated at General Motors for transportation applications require removal of carbon monoxide from the hydrogen-rich gas stream produced by the fuel processing section. A variety of catalytic materials, including noble metals (Pt, Pd, Rh, and Ru) and base metals (Co/Cu, Ni/Co/Fe, Ag, Cr, Fe, and Mn), were evaluated in a laboratory reactor feedstream containing CO, H2, and O2 in order to identify alternate catalysts which are more effective than currently used Pt/Al2O3 in selectively oxidizing CO in the presence of excess H2. Both Ru/Al2O3 and Rh/Al2O3 are among the most active catalysts for CO oxidation, achieving nearly complete CO conversion at temperatures as low as l00°C (compared to ∼200°C required for currently used Pt/Al2O3. Furthermore, the Ru/Al2O3 and Rh/Al2O3 catalysts were found to be exceptionally selective for CO oxidation, making it possible to purify the fuel cell feedstream with a minimum loss of the energy content associated with H2. © 1993 Academic Press, Inc.