Catalytic oxidations over titanosilicate zeolites

Abstract

An important topic in the field of zeolite is the titanosilicate with tetrahedral Ti sites, which have already been regarded as efficient catalyst for the oxidation of various organic substrates by hydrogen peroxide. Since the first report of TS-1 zeolite in 1983, a variety of titanosilicates with various morphologies have been synthesized and applied in the oxidation reactions. The physical parameters of structures, porosities, Ti loadings, and wettabilities strongly determine the catalytic properties of the titanosilicate catalysts. The TS-1 zeolite is efficient for the hydroxylation of benzene and phenol, as well as the epoxidation and ammoxidation of olefins and ketons with small molecule size. Ti-Beta with larger micropores than TS-1 exhibits excellent catalytic performances in the oxidation of bulky molecules. Ti-MWW zeolites with a unique two-dimensional structure are also used in the oxidation of olefins, ammoxidation of ketons, and oxidative desulfurization.