Preparation, characterization and catalytic properties of singly and doubly titanium-modified mesoporous silica gel

A series of titanium-modified mesoporous silica gel have been synthesized using tetrabutyl titanate. The samples were characterized by nitrogen adsorption–desorption, FT-IR and Raman spectroscopy, as well as by solid state diffuse reflectance UV–VIS spectroscopy. Physicochemical characterization of the materials showed that Ti atoms were part of the framework of silica gel, and it was probably in a tetrahedral coordination for low Ti contents. The resulting titania modified the inner walls of the mesoporous silica gel after hydrolysis and calcination. Actually, the titanium precursor reacted and condensed with the active silanol groups on silica gel via Si–O-Ti bonds. In addition, the titanium-modified mesoporous silica gel showed distinct activity behavior in the catalytic oxidation of cyclohexene and styrene with hydrogen peroxide as oxidant.