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 mu m 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 degrees 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. [GRAPHICS] .