Promotional effects of manganese on the structure and activity of Ce-Al-Si based catalysts for low-temperature oxidation of acetone

Abstract

Low-temperature catalytic oxidation of acetone over metal (M = Cu, Co, Ni, Mn, Fe)-modified cerium oxide supported on Al-containing MSPs (mesoporous silica particles) was studied. The activity tests on various mixed oxides of Cu-Ce, Co-Ce, Ni-Ce, Mn-Ce and Fe-Ce supported on Al-MSPs demonstrated that Ce was the main active species in catalytic oxidation of acetone, while Mn functioned as an appropriate promoter for improving the activity of Ce/Al-MSPs catalyst. The promoting effects of Mn on the structure and activity of Ce/Al-MSPs were investigated. Results showed that the amounts of Mn had significant influences on the catalyst structure, chemical state, redox behavior and surface adsorption ability of the catalysts. Among the catalysts studied, Mn-Ce/Al-MSPs with a Mn/Ce molar ratio of 2/1 was found to be the most active catalyst for achieving maximum acetone activity at temperature of 100-200 degrees C, and it showed much better catalytic performance in comparison with those of Ce/Al-MSPs and Mn/Al-MSPs alone. The superior activity could be attributed to the synergistic effect existing in MnCeOx mixed oxides, resulting in higher amount of Ce3+ and Mn4+ species and enhanced surface reducibility on the catalyst surface and improved acetone adsorption ability, as confirmed by the XPS, H-2-TPR and acetone-TPD analyses. In addition, Mn-Ce(2/1)/AI-MSPs showed a remarkable stability at 175 degrees C after being used for 55 h. (C) 2016 Elsevier B.V. All rights reserved.