Enhance catalytic activity for CO oxidation over titania supported gold catalysts that dispersed on SiO2

The enhanced dispersion of gold on TiO2 was achieved by dispersing TiO2 onto a high-surface-area SiO2 powder support. High temperature reduction, at 773–873 K, in hydrogen leads to very active gold nanoparticles on the support surfaces for CO oxidation at room temperature. The surface sol–gel method results better dispersion for both TiO2 and Au, and higher activity for CO oxidation than that by the conventional impregnation method. Metallic gold with slightly negative charge was evidenced by X-ray photoelectron spectroscopy (XPS) and in situ transmission infrared spectroscopy (FTIR) using CO as a probe. The obtained Au/TiO2/SiO2 catalysts show better stability and higher activities for CO oxidation than that for Au/TiO2. The promotion effects may origin from the formation of thin layer and small crystalline particles of TiO2 anchored on SiO2, leading to a better dispersion of small Au nanoparticles and sinter resisting.