Synthesis, characterization and catalytic activity of Au/Ce0.8Zr0.2O2 catalysts for CO oxidation

Nanostructure Ce0.8Zr0.2O2 powders used as the support were synthesized by a hydrothermal route and the Au/Ce0.8Zr0.2O2 catalysts were prepared via deposition-precipitation method. The samples were characterized by X-ray diffraction pattern (XRD), Fourier transform Raman spectra (FT-Raman), high-resolution transmission electron microscope (HRTEM), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR) techniques. The influence of the pH values, An loadings, calcination temperature and calcination time on the catalytic activity of the Au/Ce0.8Zr0.2O2 catalysts was investigated. The suitable pH value to prepare the catalysts was 7.0 and the suitable calcination conditions were 300 degrees C and 3 h. The Au(2 wt.%)/Ce0.8Zr0.2O2 catalyst showed the best catalytic performance among all the prepared samples. TPR analysis indicated that the addition of gold can improve the reducibility of the catalyst obviously. XPS analysis revealed that both Ce4+ and Ce3+ were present on the surface of the catalyst. According to TPR and XPS analyses, the gold particles (Au-0 and Au3+) existed in the catalyst, which played an important role in the catalytic activity. XRD and XPS results showed that the high dispersion degree of gold particles on the support was responsible for the superior catalytic property. (c) 2007 Elsevier B.V. All rights reserved.