3-(2-Hydroxyl-Ethyl)-1-Propylimidazolium Bromide Immobilized on SBA-15 as Efficient Catalyst for the Synthesis of Cyclic Carbonates via the Coupling of Carbon Dioxide with Epoxides

3-(2-hydroxyl-ethyl)-1-propylimidazolium bromide (HEPIMBr) was immobilized onto SBA-15, Al-SBA-15 mesoporous molecular sieves and SiO2 by chemical grafting method. The materials were characterized and used as catalysts for solvent-free synthesis of cyclic carbonates from CO2 and epoxides under relatively mild conditions. Among them, the HEPIMBr immobilized on SBA-15 performs the best, showing carbonate selectivity and yield of ca. 100% (120 degrees C, 2.0 MPa, 2 h). The catalyst is thermally stable and shows good reusability. Based on the experimental results, a plausible reaction mechanism has been proposed for the catalytic reaction.