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.

In-situ synthesis of monolithic Cu-Mn-Ce/cordierite catalysts towards VOCs combustion

A monolithic series of Cu-Mn-Ce oxides supported on cordierites with different Cu/Mn/Ce molar ratios were prepared by the in-situ sol-gel method without any binder. The catalysts were characterized by scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS）, X-ray diffraction （XRD）, and Brunauer-Emmett-Teller method （BET） and examined in the catalytic combustion of volatile organic compounds （VOCs）. The results showed that the well-dispersed nanometer particles of mixed oxides adhered firmly to the cordierite surface. Cu0.15Mn0.3Ce55/cordierite was identified as the most active catalyst. Compared with commercial Pd/Al2O3, Cu0.15Mn0.3Ce55/cordierite showed higher activities for the combustion of various types of VOCs, especially for oxy-derivative compounds which could be lighted off below 200 ℃.