KINETICS OF CO OXIDATION ON CU/RH(100) MODEL BIMETALLIC CATALYSTS

The oxidation of carbon monoxide has been studied on a series of Cu/Rh(100) model bimetallic catalysts using a combined elevated pressure reactor-ultrahigh vacuum surface analysis system. The effects of temperature and oxygen/carbon monoxide partial pressures on the rates of CO2 formation and surface composition/morphology were determined. Although the addition of copper to Rh(100) altered the rate of CO oxidation, the kinetic behavior of the Cu/Rh(100) catalysts was essentially the same as that for Rh(100) with modifications within the low Cu coverage region, i.e., at θCu < 0.5 ML. The altered kinetics are attributed to two types of reaction sites at these low Cu coverages. The primary role of copper in the Cu/Rh(100) bimetallic catalyst is to increase the surface oxygen coverage. The presence of Cu and Rh carbonate-like surface species was evident in postreaction TPD analysis. © 1994 Academic Press, Inc.