A highly efficient and stable Au–Cu/hydroxyapatite (HAP, Ca10(PO4)6(OH)2) catalyst was reported. HAP was prepared through a deposition–precipitation method. Au–Cu/HAP catalysts were obtained by a two-step impregnation approach. The samples were characterized by XRD, TEM, SEM, UV-Vis, ICP, XPS, H2-TPR, and O2-TPD. CO oxidation reaction was carried out to evaluate the catalytic performance of samples. TEM and UV-Vis results showed that the metallic particles supported on Au–Cu/HAP were smaller than those on Au/HAP, and they were highly dispersed on the HAP support. Patterns of XPS revealed that CuO nanoparticles were formed in the Cu/HAP catalyst, while CuO and Cu2O species coexisted in Au–Cu/HAP catalyst. Based on the O2-TPD data, the addition of copper to Au/HAP gave rise to more new O2 adsorption sites and bigger O2 adsorption capacity. The catalysis results indicated that the Au–Cu/HAP was capable of obtaining higher efficiency and stability compared with Au/HAP and Cu/HAP for CO oxidation. It was likely that the synergistic interaction between gold and CuOx phase created the most active sites on Au–Cu/HAP and was responsible for the enhanced activity and stability in comparison with Au/HAP and Cu/HAP.
In this work, ruthenium-based bimetallic catalysts of 1Ru-5 M/TiO 2 (M = Co, Ce, Fe, Mn, Cu, Ni) were prepared and evaluated in ethyl acetate oxidation. It was found that 1Ru-5Cu/TiO 2 gave the highest catalytic activity. The influence of CuO content and the preparation method on the catalytic activity was also studied. 1Ru-5Cu/TiO 2 showed great catalytic stability in the on-stream reaction test. The influence of H 2 O on the catalytic activity is presented. The bimetallic catalyst 1Ru-5Cu/TiO 2 showed better catalytic performance than the monometallic catalysts 1Ru/TiO 2 and 5Cu/TiO 2 . 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 RuO 2 surface . Accordingly, a reaction mechanism for the catalytic oxidation of ethyl acetate over a Ru-Cu bimetallic catalyst is proposed.
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