CO OXIDATION OVER Rh AND Ru: A COMPARATIVE STUDY

Article abstract of DOI:10.1021/j100411a024

The oxidation of CO over Ru and Rh single crystals has been studied in a high-pressure reaction-high -vacuum surface analysis apparatus.Steady-state catalytic activity as a function of temperature and partial pressure of CO and O2 has been measured.Both the specific rates and the relative activity (Ru > Rh) obtained in this study compare very favorably with results found for high area supported catalysts.Surface concentrations of oxygen were monitored following reaction and found to be dependent on the partial pressures of the reactants.For Ru, the highest rates of reaction correspond to reaction on a Ru surface covered with a monolayer of oxygen as detected subsequent to reaction by Auger spectroscopy.For Rh, the reaction was found to be inhibited by an oxygen covered surface.These results suggest an explanation for the relative activites (Rh > Ru) observed in ultrahigh vacuum measuraments for this reaction on clean surfaces of Ru and Rh.