Epoxidation of Styrene with H2O2 Catalyzed by Alanine–Salicylaldehyde Schiff Base Chromium (III) Complexes Immobilized on Mesoporous Materials

Abstract

Alanine–salicylaldehyde Schiff base chromium (III) complex was immobilized on mesoporous silica gel (SiO2), MCM-41 and SBA-15. The resulting immobilized complexes were promising catalysts for the epoxidation of styrene with 30% hydrogen peroxide, and they all showed much higher catalytic performance than their homogeneous analogue. Simultaneously, the catalytic performance of immobilized complexes was found to be closely related to the textual and surface properties of the supports used. The complex immobilized on methyl-containing MCM-41 exhibited the highest catalytic performance. Under optimal reaction conditions, the highest conversion of styrene reached 80.2% with 77.0% selectivity to epoxide. In addition, the catalytic performance remained stable after six times of recycling. A series of immobilized alanine–salicylaldehyde Schiff base chromium (III) complexes were promising catalysts for the epoxidation of styrene with 30% hydrogen peroxide. Moreover, the different textural and surface properties of supports significantly influenced their catalytic performance.