Polymer-supported Quaternary Phosphonium Ionic Liquid Catalysts for Efficient Fixation of CO2 into Cyclic Carbonates

The chemical conversion of CO2 into cyclic carbonate is an effective method for the resource utilization of CO2 and the production of cyclic carbonates. Herein, a series of polymer-supported quaternary phosphonium ionic liquid catalysts with high grafting amount have been systematically designed and synthesized, and all catalysts could promote efficient fixation of CO2 into cyclic carbonate. According to the results of the experiment and simulation, it was found that the high catalytic activity was ascribed to the weak interaction energy of the anion and cation of the catalyst. Among them, PS-TPP-Cl, with lower interaction energy of 72.2 KJ/mol, showed better performance. Yet even after being recycled five times, its conversion of propylene oxide with little loss was still above 95 %. Furthermore, a possible cycloaddition mechanism for the synergetic effect of cation-anion coordination has been proposed. This work will shed new light on the development of novel heterogeneous catalysts with promising properties for industrial applications.