Incorporation of Carboxyl-Functionalized Imidazolium-Based Ionic Liquid into a UiO-66 Type MOF for Chemical Fixation of CO2 into Carbonates

Abstract

Incorporation of Ionic liquid into a metal organic frameworks (MOFs) offer a new platform to construct heterogeneous bifunctional catalytic systems for the chemical capture and conversion of CO2 with epoxides. Herein, imidazolium-based ionic liquid decorated UiO-66 type MOF (P3[BCMIm]Br@UiO-66) was successfully constructed via solvothermal assembly of the carboxyl-functionalized imidazolium ionic liquid ligand, terephthalic acid ligand and Zr(IV) ions. It exhibits the highest catalytic activity upon the cycloaddition of CO2 (98.2% conversion of Propylene oxide, 99% selectivity to Propylene Carbonate) under optimized conditions (2.2 Mpa CO2, 1.0 wt.%, 110 °C, reaction time 2 h). Notably, the catalytic performance of P3[BCMIm]Br@UiO-66 outperformed that of the original UiO-66 materials and [BCMIm]Br. [BCMIm]Br@UiO-66 retained good catalytic performance for up to five recycling runs with only a little loss in catalytic activity. Futhermore, several additional coupling reactions were investigated with other epoxides as substrates.