Creation, characterisation and performance of vanadyl active sites in microporous and mesoporous silica-based catalysts for the selective oxidation of hydrocarbons

We here describe how to design vanadium-centred active sites at the inner surfaces of both well defined microporous and well defined mesoporous siliceous hosts. Each type of vanadia-silica catalyst has been extensively characterised (in regard to surface area, pore size and hydrophobicity) and X-ray absorption spectroscopy establishes the active site for these conversions to be a vanadyl group. These centres are catalytically active under mild conditions for both the epoxidation of a typical alkene and the selective oxidation of a typical alkane. Placing methyl groups in the vicinity of this active site significantly enhances the catalytic performance towards epoxidation.