Immobilized Brønsted ionic liquids: Heterogeneous catalyst for synthesis of cyclic carbonates from carbon dioxide and epoxides

A wide variety of immobilized Brønsted acidic ionic liquids immobilized onto a cross-linked polystyrene resin (PS) are synthesized. The structure of the ionic liquids are characterized. The catalytic performance of these immobilized ionic liquids for the synthesis of cyclic carbonates via the cycloaddition reaction of CO₂ with epoxides is studied, and the reaction conditions are investigated and optimized. As a result, high yield of 92.7% of propylene carbonate could be achieved at optimal conditions, 2.0 MPa and 120°C for 3 h by using the carboxyl-isobutyl-functionalized Immobilized ionic liquids (PS-HBIMBr.) as catalyst. And the catalysts shows excellent reusability for the cycloaddition reaction of CO₂ with epoxides.