Carboxy-functionalized imidazolium ionic liquid immobilized on MCM-41 as recyclable catalysts for carbon dioxide conversion to cyclic carbonates

Abstract

Integrating multifunctional active sites into an appropriate porous material is a promising strategy to achieve great catalytic performance for CO2 cycloaddition. Herein, carboxy-functionalized imidazolium ionic liquid were successfully anchored onto the MCM-41 mesoporous silicates. The resultant MCM-41-Imi/COOH integrates hydrogen bond donor, Lewis base and nucleophilic ionic sites, and possesses a high surface area and mesopore structure. As-prepared catalyst achieves a good catalytic activity for CO2 cycloaddition with propylene oxide under cocatalyst- and solvent-free conditions. Moreover, the catalyst MCM-41-Imi/COOH exhibits the good cycling stability and versatility to various epoxides. In particular, the catalyst shows a satisfactory catalytic activity for catalyzing dilute CO2 conversion to cyclic carbonate. Furthermore, a possible reaction mechanism for the cycloaddition of CO2 with propylene oxide over the catalyst MCM-41-Imi/COOH was proposed.