CATALYST OF GOLD PARTICLES ON A MIXED SUPPORT FOR SELECTIVE OXIDATION OF CO IN THE PRESENCE OF H2

摘要

A hydrogen-air polymer electrolyte membrane (PEM) fuel cell is potentially an attractive and clean energy source for vehicle propulsion and auxiliary power units. The hydrogen used therein is produced locally from gasoline, methanol or natural gas via steam-reforming, or partial oxidation combined with water-gas shift reaction processes. However, the product stream Of H2 and CO2 obtained therefrom is usually contaminated with at least 1-2 vol% CO which acts as a poison for the anode catalyst (generally Pt- based) at operating temperatures of about 60 - 150 0C. It is now found that a catalyst comprising highly dispersed gold nanoparticles on an alumina or zirconia support, wherein the support further comprises CeOx and Li2O, can selectively convert the CO concentration in the reformer gas towards CO2. It thus avoids the oxidation of hydrogen, and yields almost full CO conversion over the whole range of temperatures relevant for PEM fuel cells, i.e. 60 - 150 0C, even at high oxygen and hydrogen concentrations. The catalyst of the invention shows a beneficial effect over other catalysts known in the art, which catalysts usually show a drop in CO conversion at temperatures higher than 50 0C.