Cu-Co mixed oxide catalysts for the total oxidation of toluene and propane

Cu-Co mixed oxides were fabricated via co-precipitation, characterized by TG/DTA, FTIR, ICP, XRD, Raman and CO-TPR, and tested in the total oxidation of toluene and propane. Adding an appropriate amount of copper to cobalt oxide caused structural defects and weakened the Co-O bond, thereby benefiting the activation of oxygen. Moreover, the reducibility of Co3O4 was greatly improved in the presence of copper. In terms of toluene oxidation, a promoting effect of Cu was observed in both activity and durability, which could be related to the enhanced redox ability induced by the strong Cu-Co interaction and the inhibitory effect of Cu on the accumulation of surface carbonaceous species, respectively. Cu0.2Co exhibited the best toluene oxidation performance (T-90 = 240 degrees C) and excellent long-term durability. On the other hand, in propane oxidation, the activity of the Cu-Co catalysts decreased dramatically as the copper content increased, due to the extremely low intrinsic activity of CuO. The effects of CO2, water vapor and NO on propane oxidation over Co3O4 and Cu0.2Co were also examined.