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

[Display omitted] •Promoted redox ability of Co3O4 by Cu addition via co-precipitation.•Enhanced toluene oxidation efficiency and durability on Cu-Co oxide.•Poisoning effect of Cu on propane oxidation activity of Co3O4.•Inhibitory effect of Cu on the accumulation of surface carbonaceous species.•Irreversible deactivation of the catalysts caused by NO introduction. 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 CoO 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 (T90 = 240 °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.