Ionic liquids supported at MCM-41 for catalyzing CO2 into cyclic carbonates without co-catalyst

A kind of heterogeneous catalyst MCM-41-S-ImBr was prepared by grafting 1-vinyl-3-ethylimidazolium bromide ([VEIM]Br) on the surface of MCM-41. The catalyst was characterized by X-ray diffraction patterns, Fourier transform infrared spectroscopy and element analysis as well as scanning electron microscopy. It showed that [VEIM]Br was successfully grafted on MCM-41 and the catalyst possessed an average particle size of 1.4 µm with intact mesoporous structure. Moreover, the catalyst exhibited high catalytic activity in the cycloaddition reaction of CO2 with epichlorohydrin without co-catalyst. The conversion of epichlorohydrin was 98.5% and the selectivity of cyclic carbonate was 98.3% at 130 °C under 1.6 MPa for 6 h. Reaction kinetic study indicated that the pseudo-first order rate constant was 0.223 ± 0.001 h−1. It is proved that MCM-41-S-ImBr could be used at least 4 times without obvious decrease in catalytic performance. A possible reaction mechanism was also proposed: the quaternary imidazolium ion cooperatively worked with the bromide ion to catalyze the reaction.