Design of CeMnCu ternary mixed oxides as soot combustion catalysts based on optimized Ce/Mn and Mn/Cu ratios in binary mixed oxides

Ternary Ce-Mn-Cu mixed oxides as soot oxidation catalysts have been designed and prepared by co-precipitation method (getting CMC-Cp) or impregnation (CMC-Imp), based on the already optimized Ce/Mn and Mn/Cu ratios. Several corresponding binary and single oxides were also prepared for reference. It turned out that the coprecipitation method could produce catalysts with high S am , small grain size as well as enhanced reducibility and catalytic activity compared to the impregnation method. Among all the catalysts, CMC-Cp-c which was based on the assumption that Ce-Mn-O and Mn-Cu-O components are independent from each other, showed the best catalytic activity. Based on the rich sample library, the positive correlation between reducibility and catalytic activity, and that between the average valence state of the dominant Ce and reducibility (or catalytic activity) were established. Furthermore, the effect of soot and/or H2O addition on NO oxidation, and that of H2O addition on soot combustion were thoroughly studied.