Catalytic oxidation of ethyl acetate over Ru-Cu bimetallic catalysts: Further insights into reaction mechanism via in situ FTIR and DFT studies

In this work, ruthenium-based bimetallic catalysts of 1Ru-5 M/TiO2 (M = Co, Ce, Fe, Mn, Cu, Ni) were prepared and evaluated in ethyl acetate oxidation. It was found that 1Ru-5Cu/TiO2 gave the highest catalytic activity. The influence of CuO content and the preparation method on the catalytic activity was also studied. 1Ru-5Cu/TiO2 showed great catalytic stability in the on-stream reaction test. The influence of H2O on the catalytic activity is presented. The bimetallic catalyst 1Ru-5Cu/TiO2 showed better catalytic performance than the monometallic catalysts 1Ru/TiO2 and 5Cu/TiO2. XRD, TEM, HAADF-STEM, H-2-TPR, and XPS characterizations were conducted, and the synergistic effect between Ru and Cu was well presented. In situ FTIR studies were also conducted, and the reaction intermediates were revealed on the catalyst surface. The theoretical calculations suggested that ethyl acetate is more easily adsorbed on the CuO surface, while it reacts more easily on the RuO2 surface. Accordingly, a reaction mechanism for the catalytic oxidation of ethyl acetate over a Ru-Cu bimetallic catalyst is proposed. (C) 2018 Elsevier Inc. All rights reserved.