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

Abstract

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 CuO_x 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.