Catalytic Performance and Reaction Mechanisms of Ethyl Acetate Oxidation over the Au–Pd/TiO2 Catalysts

The development of efficient and stable catalysts is of great importance for the elimination of volatile organic pollutants (VOCs). In this work, AuPdxnanoparticles (NPs) were loaded on TiO2through the electrostatic adsorption approach to generate theyAuPdx/TiO2(i.e., 0.35AuPd0.46/TiO2, 0.34AuPd2.09/TiO2, and 0.37AuPd2.72/TiO2;xandyare Pd/Au molar ratio and AuPdxloading, respectively;x= 0.46–2.72; andy= 0.34–0.37 wt%) catalysts, and their catalytic activities for the oxidation of ethyl acetate were determined. The results showed that the 0.37AuPd2.72/TiO2sample exhibited the best activity (T50%= 217 °C andT90%= 239 °C at SV = 40,000 mL/(g h),Ea= 37 kJ/mol, specific reaction rate at 220 °C = 113.8 µmol/(gPds), and turnover frequency (TOFNoble metal) at 220 °C = 109.7 × 10−3s−1). The high catalytic performance of the 0.37AuPd2.72/TiO2sample was attributed to the good dispersion of AuPd2.72NPs, the strong redox ability, the large ethyl acetate adsorption capacity, and the strong interaction between AuPdxand TiO2. Acetaldehyde, ethanol, and acetic acid are the main intermediates in the oxidation of ethyl acetate, and the loading of AuPdxNPs effectively reduces the formation of the toxic by-product acetaldehyde. The oxidation of ethyl acetate over the 0.34AuPd2.09/TiO2sample might occur via the pathway of ethyl acetate → ethanol → acetic acid → acetate → CO2and H2O. We believe that the obtained results may provide a useful idea for the design of bimetallic catalysts under industrial conditions and for understanding the VOCs oxidation mechanisms.Keywords:supported Au–Pd nanocatalyst;ethyl acetate oxidation;strong electrostatic adsorption;sulfur dioxide resistance;reaction mechanism