Hydrophobic fluorinated TiO 2–ZrO 2 as catalyst in epoxidation of 1-octene with aqueous hydrogen peroxide

Abstract

A new heterogeneous oxidation catalyst was prepared by impregnation of TiO 2 from titanium(IV)tetra-2-propoxide on the surface of ZrO 2. The surfaces of TiO 2–ZrO 2 particles were then modified by the fluorination of ammonium hexafluorosilicate and followed by alkylsilylation of n-octadecyltrichlorosilane (OTS). The resulting catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption isotherm, UV–Vis Diffuse Reflectance (UV–Vis DR), and Energy Dispersive X-Ray Analysis (EDAX) techniques. The catalytic potential of catalysts for oxidation reactions has been verified in the liquid phase epoxidation of 1-octene to 1,2-epoxyoctane with aqueous hydrogen peroxide. It is demonstrated that the fluorination and alkylsilylation enhance the catalytic activity of TiO 2–ZrO 2. A high catalytic activity of the modified TiO 2–ZrO 2 was related to the modification of the local environment of titanium active site and increasing the hydrophobicity of catalyst particles by fluorination and alkylsilylation.