Effects of Cu oxidation states on the catalysis of NO+CO and N2O+CO reactions

Abstract The relationship between the oxidation state of bulk Cu and catalytic activity during the NO + CO and N 2 O + CO reactions were investigated, using commercially available Cu, Cu 2 O and CuO powders. Metallic Cu powder was found to catalyze both reactions in a stable manner without changing its oxidation state. At elevated temperatures, the catalytic activities of the Cu 2 O and CuO increased with time, in conjunction with reduction by CO to metallic Cu in both cases. The data confirm that metallic Cu exhibits much high activity and stability than either Cu 2 O or CuO for both the NO + CO and N 2 O + CO reactions. In addition, Cu 2 O species (denoted as Cu 2 O*) formed via oxidation of metallic Cu species obtained by reduction of CuO with CO at low temperature (