Catalytic oxidation of CO by platinum group metals: from ultrahigh vacuum to elevated pressures

CO oxidation over platinum group metals has been investigated for some eight decades by many researchers and is considered to be the best understood catalytic reaction. Nevertheless, there has been a renewed interest in CO oxidation recently because of its technological importance in pollution control and fuel cells. Removal of COx from automobile exhaust is accomplished by catalytic converters using supported Pt, Pd and Rh catalysts. Catalysts are used in fuel cells to remove traces of COx from the H2 feed gas to the few ppm level necessary for their efficient operation. Efforts have been made in our laboratory to understand the adsorption of CO and the kinetics of CO-oxidation on both single crystals and supported metal catalysts over a wide temperature (100 /1000 K) and pressure (1 /10 7 /10 Torr) range. By comparing the results of single crystals, model supported catalysts, and supported technical catalysts the relationship between particle size and catalytic activity can be better understood. Also discussed is CO oxidation on model supported Au catalysts, a promising new candidate for low temperature CO oxidation. # 2002 Published by Elsevier Science Ltd.