Vapor Phase Oxidation of Benzyl Alcohol Over Gold Nanoparticles Supported on Mesoporous TiO2

The vapor phase oxidation of benzyl alcohol was investigated over gold nanoparticles supported on mesoporous titanium dioxide (anatase) catalysts under aerobic conditions. The catalysts were prepared by homogeneous deposition–precipitation method using urea as the precipitating agent. The physico-chemical properties of the synthesized catalysts were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), pore size distribution (PSD), CO-chemisorption and X-ray photoelectron spectroscopy (XPS) techniques. The crystallite size of gold in Au/TiO 2 catalysts was measured from XRD. The mesoporosity of TiO 2 support and Au/TiO 2 catalysts were confirmed by PSD analysis. TEM results suggest that gold nanoparticles are well dispersed over mesoporous TiO 2 . The catalytic functionality is well substantiated with particle size measured from TEM. XPS results reveal the formation of Au(0) after chemical reduction by NaBH 4 . The vapor phase benzyl alcohol oxidation was used as a test reaction to investigate the influence of the metal, nature of the support, and of metal-support interactions in Au/TiO 2 catalysts and also the catalytic activity and stability of the Au/TiO 2 catalysts. The conversion of benzyl alcohol was found to increase with decrease in the size of gold particles. Smaller gold particles and a higher amount of small gold particles had a beneficial effect on the catalytic activity. The catalytic activity in the presence of oxygen is believed to be associated with the transport of electrons through the catalyst to the adsorbed oxygen on the surface. Graphical Abstract .