Graphene-reinforced polyimidazole microspheres as heterogeneous catalysts for catalyzing CO2 conversion to cyclic carbonates

In this work, a novel graphene-reinforced polyimidazole microsphere catalyst with dual functionality for both CO 2 adsorption and epoxide activation was successfully synthesized via one-step suspension polymerization strategy. This heterogeneous catalyst contained no halogens, effectively mitigating environmental pollution, equipment corrosion, and ensuring product quality. Specifically, graphene was strategically incorporated into the catalyst matrix during synthesis to enhance its thermal stability, and the thermal decomposition temperature has increased by 23 °C. Under optimized reaction conditions, the catalysts with high nitrogen content ( e.g. G-NCHSM-1) achieved the highest yield of cyclic carbonate (99 %) from the cycloaddition of epoxide and CO 2 . Notably, the graphene-reinforced polyimidazole catalyst exhibited favorable stability and potential for industrial applications. Finally, based on the experimental characterizations and density functional theory (DFT) calculations, a possible mechanism for the synthetic cyclic carbonate was proposed, elucidating the synergistic effect of the imine group and C β -H on the imidazole ring in catalyzing the synthesis of cyclic carbonates from CO 2 . Therein, the imine group could capture CO 2 and activate epoxides.