Modified Ag/TiO₂ systems: Promising catalysts for liquid-phase oxidation of alcohols

The current work is the first study concerning the liquid-phase oxidation of n-octanol and betulin over modified and unmodified Ag/TiO₂ catalysts. Catalytic activity of nanosilver catalysts supported on titania for alcohols selective oxidation can be enhanced by modification of the support with Ce, Fe or Mg oxides. In most cases reductive or oxidative pretreatments of these catalysts were detrimental for their activity. The main reason for performance of Ag/M_xO_y/TiO₂ catalysts is changes of the electronic state of the supported Ag, and especially changes in the surface concentration of Ag⁺ ions. Monovalent Ag⁺ ions are active sites in silver-containing catalysts for n-octanol, as well as for betulin oxidation. The obtained results show a potential of silver-containing catalysts for liquid phase oxidation of alcohols, and by selecting the optimum modifier and the support as well as, pretreatment conditions the catalytic properties and stabilization of the active sites can be optimized.