Effect of Ni Addition on the Low Temperature Carbon Monoxide Oxidation over Au/HAP Nanocatalyst

Supported gold catalysts with their uniquely catalytic properties have found extensive applications. A challenge for gold catalyst research is now to prevent the sintering of gold particles at high temperature maintaining their high activities simultaneously. Herein, Au/Ni-HAP catalyst with high activity and sintering-resistance was prepared by a deposition-precipitation method. Samples were characterized by XRD, TEM, SEM, UV-Vis, ICP, XPS, FT-Raman and O-2-TPD, and their catalytic performance for CO oxidation was tested. TEM results indicated that Au/Ni-HAP catalyst had the smaller gold nanoparticles than Au/HAP catalyst. In UV-Vis spectra, the addition of Ni to Au/HAP catalyst gave rise to larger absorption into visible light, changing the electronic structure of Au/HAP catalyst. Based on XPS studies, nickel existed mainly as NiO in Au/Ni-HAP catalyst, and a small amount of Ni(OH)(2) also was formed in Au/Ni-HAP catalyst. Profiles of O-2-TPD revealed that Au/Ni-HAP catalyst performed bigger adsorption of oxygen and possessed more new oxygen adsorption sites compared with Au/HAP catalyst. Results showed that Au/Ni-HAP catalyst had better catalytic activity and sintering-resistance than Au/HAP catalyst. The enhanced activity could be attributed to the synergistic effect of gold, nickel and HAP in Au/Ni-HAP catalyst, which created plenty of oxygen vacancies and changed the electronic structure of Au/HAP catalyst.