Green Oxidation of n‐Octanol on Supported Nanogold Catalysts: Formation of Gold Active Sites under Combined Effect of Gold Content, Additive Nature and Redox Pretreatment

Abstract

AbstractThe combined influence of gold content (0.5 or 4 wt. %), modifying additives (La or Ce oxides) and redox pretreatments (H2 or O2) on catalytic properties and formation of active sites of Au/TiO2 in the selective oxidation of n‐octanol under mild conditions was studied. Samples were characterized by BET, XRD, EDX, ICP, TEM, STEM‐HAADF, CO2‐TPD, H2‐TPR and XPS methods. The order of catalytic activity depended on the support nature for all treated samples, as follows: Au/La2O3/TiO2>Au/CeO2/TiO2>Au/TiO2. The catalytic activity enhanced with the increase of gold loading in the samples with hydrogen pretreatment, while after the oxidative pretreatment of the catalysts the opposite dependence of the activity with the gold content was found. This catalytic behavior was explained by a change in the surface concentration of monovalent gold ions, which seemed to be the active sites. The most active catalyst, 0.5 % Au/La2O3/TiO2, pretreated in oxidative atmosphere, had the highest surface concentration of monovalent gold ions.