Cu–Mn–Ce ternary mixed-oxide catalysts for catalytic combustion of toluene

Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1：2：4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the Ce O2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.

Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the xPd/OMS-2 catalysts： Effect of Pd loading

The Pd catalyst supported on cryptomelanetype manganese oxide octahedral molecular sieve （OMS- 2） were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over xPd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the xPd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/ OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 ℃, and the temperature for 90% conversion was 55,285 and 200 ℃ for oxidation of CO, toluene, and ethyl acetate, respectively. The low- temperature reducibility and high oxygen mobility ofxPd/ OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.