High efficiency and stability of Au-Cu/hydroxyapatite catalyst for the oxidation of carbon monoxide

A highly efficient and stable Au-Cu/hydroxyapatite (HAP, Ca-10(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, H-2-TPR, and O-2-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 O-2-TPD data, the addition of copper to Au/HAP gave rise to more newO(2) adsorption sites and bigger O-2 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.