High Density Poly(ionic liquid)s with Spatial Structure Regulation for Efficient Carbon Dioxide Cycloaddition

The synthesis of cyclic carbonate from CO2 and epoxide is one of the valid routes in line with atomic economy to achieve CO2 conversion. Combining the advantages of high activity and easy separation for heterogeneous catalytic reaction system, a series of heterogeneous catalysts poly(ionic liquid)s with high ionic density (HDPILs) were designed and synthesized. Looser structures and high ionic density were obtained by using muti-center ionic liquids with different number of substituents as cross-linking agents. Ply[PhSVIM]Br, the copolymerized HDPILs with six substituents on the benzene ring was optimal. The catalyst exhibited excellent catalytic performance for CO2 cycloaddition with 98 % conversion and 99 % selectivity under optimal conditions. These HDPILs have comparable catalytic activity to homogeneous catalysts and convenient product separability. Particularly, combining XPS and DFT, a structural performance relationship was revealed, the multi-center ionic liquids used instead of the traditional crosslinking agent as the polymeric backbone can contribute to the reduction of the anion and cation binding energy (BE) and freeing of Br-, which leads to efficient catalytic activity. This study provides a novel strategy for developing a highly efficient catalysts for CO2 conversion to high value products.

Automated summary

This study designed and synthesized poly(ionic liquid)s catalysts with high ionic density for the synthesis of cyclic carbonate from CO2 and epoxide. The catalyst exhibited excellent catalytic performance, comparable to homogeneous catalysts, with convenient product separability. This research provides a novel strategy for developing highly efficient catalysts for CO2 conversion to high value products.