Immobilization of Mn(salen) complex on aluminum-containing mesoporous materials by microwave heating for epoxidation of styrene

Abstract

Al-contianing mesoporous silicates (Al-MCM-41 and Al-HMS) supported Mn(salen) catalysts have been prepared by three different methods: impregnation of salen ligand and support with dichloromethane and then irradiated by microwave (method A), direct solid-state interaction between salen complex and support under microwave irradiation (method B), as well as the conventional ion exchange (method C). The combined characterization of FT-IR, UV-Vis spectra and TG-DSC analysis reveal that Mn(Salen) complex can be immobilized successfully on mesoporous materials by a strong guest/host interaction of the aromatic rings of the salen complex with the silanol groups on the walls of the mesopores. The effect of catalyst preparation methods on the catalytic activity and selectivity in the styrene epoxidation indicate that the catalyst of Mn(Salen)/Al-HMS-IP prepared by method A shows similar activity to the neat complex and the best selectivity for styrene epoxide. The reuse of the Mn(Salen)/Al-HMS-IP catalyst shows no leaching of salen ligand and identification of Mn(Salen) complex immobilized on the mesoporous materials.