Solventless synthesis of cyclic carbonates from carbon dioxide and epoxides catalyzed by silica-supported ionic liquids under supercritical conditions

A silica-supported ionic liquid proved to be an efficient heterogeneous catalyst for solventless synthesis of cyclic carbonates from epoxides and carbon dioxide under supercritical conditions, which requires no additional organic solvents either for the reaction or for the separation of product. The effects of reaction time, temperature and other reaction parameters on the reaction are investigated. High yields with excellent selectivity were obtained. The purity of product separated directly by filtration from the reaction mixture, reached 99% without further purification process. Moreover, the catalyst can be easily recovered by filtration and reused over four times with slight loss of its catalytic activity. The process represents a simple, ecologically safer, cost-effective route to cyclic carbonates with high product quality, as well as easy product recovery and catalyst recycling.