Imidazolinium based porous hypercrosslinked ionic polymers for efficient CO2 capture and fixation with epoxides

Abstract

The efficient capture and chemical conversion of carbon dioxide (CO₂) requires a solid simultaneously with a large surface area and highly effective active sites. Herein, imidazolinium based porous hypercrosslinked ionic polymers (HIPs) with a high surface area, rich micro/mesoporosity and abundant ionic sites were constructed via the hypercrosslinkage of 2-phenylimidazoline and benzyl halides, in which quaternization and Friedel–Crafts alkylation happened simultaneously to afford ionic polymeric networks. The obtained HIPs were efficient in the selective capture of CO₂ and cycloaddition of CO₂ with epoxides. High yield, stable reusability and good substrate compatibility were achieved under mild conditions (down to ambient conditions), dramatically outperforming the homogeneous ionic liquid monomer and post-modified analogues. The synergistic adsorption and conversion enabled the efficient low-temperature conversion of diluted CO₂ (0.15 bar CO₂ and 0.85 bar nitrogen, the simulation of flue gas) catalyzed by HIPs in the presence of co-catalyst ZnBr₂. The in situ formed ionic sites with a high leaving ability being homogeneously embedded in the hypercrosslinked polymeric skeleton responded to the high adsorption and catalysis performance. This work highlights the functional HIPs as a versatile platform to reach efficient CO₂ capture and conversion under mild conditions.