Transition Metal-immobilized Silica Catalysts for Selective Oxidation of Cyclohexane with t-Butyl Hydroperoxide

Abstract

Transition metal-immobilized silica catalysts, M/SiO2 (M = Co, Cu, Mn, Cr and Ni) have been prepared by the sol-gel technique and characterized by means of X-ray diffraction, N2-physisorption, ICP and FTIR. They have been used as heterogeneous catalysts for selective oxidation of cyclohexane to cyclohexanol and cyclohexanone with anhydrous tert-butylhydroperoxide (TBHP). All the M/SiO2 catalysts prepared provided relatively high conversion and selectivity . The reaction mechanism was found to involve free peroxyl radicals. The Co/ SiO2 was the most active catalyst and after calcination the conversion of cyclohexane was increased but selectivity to cyclohexanone was decreased.