Efficient catalytic ozonation of ethyl acetate over Cu-Mn catalysts: Further insights into the reaction mechanism

Abstract

A series of Cu-Mn oxides were synthesized by the redox-precipitation method with different precipitants to evaluate the catalytic ozonation of ethyl acetate (EA). It was found that CuMn-II (with H2C2O4 as precipitant) exhibited the best catalytic activity, which achieved an EA conversion of 99 % at 120 °C with an O3/EA molar ratio of 10. The reaction temperature, O3/EA molar ratio, ozone utilization rate, and COx selectivity were also discussed. Meanwhile, many characterizations were conducted to reveal the properties of catalysts, such as SEM, XRD, BET, XPS, H2-TPR and NH3-TPD. Abundant surface defects, plentiful oxygen vacancies, larger specific surface area, higher content of Mn3+ and more acid sites contributed to the superior performance of CuMn-II. Catalyst poisoning occurred when SO2 was added, however, the conversion of EA could gradually recover to 88 % once SO2 was stopped. In-situ DRIFTS measurement was carried out to reveal the formation of intermediate species during the reaction. Combined with DFT calculations, a reaction mechanism for the catalytic ozonation of EA over CuMn2O4 catalysts was proposed.