Correlation between the physicochemical properties and catalytic performances of micro/mesoporous CoCeOx mixed oxides for propane combustion

A series of micro-mesoporous CoCeOx catalysts have been successfully prepared using a double template combining sol-gel method. The catalytic performance of novel CoCeOx catalysts are investigated and compared with pure Co3O4 and CeO2 catalysts for total oxidation of propane. It is found that the Co1Ce1 catalyst shows the highest catalytic activity (T-55 = 217 degrees C) as well as a good reaction stability and water tolerance among the five catalysts. The Co3O4, CeO2 and CoCeOx catalysts are characterized using XRD, BET, Raman, XPS, H-2-TPR, O-2-TPD, HRTEM, HAADF-STEM and in situ DRIFTS. The results demonstrate that the larger BET surface area, smaller grain size, stronger reducibility and more active oxygen species of the Co1Ce1 catalyst are responsible for its outstanding catalytic performance among the five catalysts. Moreover, the synergistic effect between Co and Ce over CoCeOx catalysts are probably relevant to the formation of CoxCe1-xO2-sigma solid solution. In addition, on the basis of the results of XPS, kinetic analysis and in situ DRIFTS, the surface Co3+ ions and active oxygen species are regarded as the major active sites of the CoCeOx catalysts for total oxidation of propane, and then a scheme of reaction model based on Langmuir-Hinshelwood mechanism is suggested at last. It can be expected that the micro-mesoporous CoCox catalysts are promising materials for VOCs removal, and the results in this research may also provide some new insights into the catalyst design and mechanism exploration for VOCs catalytic oxidation.