Incorporation of a carboxyl-functionalized imidazolium-based ionic liquid into a UiO-66 type MOF for chemical fixation of CO2 into carbonates

Incorporation of ionic liquids into metal-organic frameworks (MOFs) offers a new platform to construct heterogeneous bifunctional catalytic systems for the chemical capture and conversion of CO2 with epoxides. Herein, an 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 and 99% selectivity to propylene carbonate) under optimized conditions (2.2 Mpa CO2, 1.0 wt%, 110 degrees C, reaction time 2 h). Notably, P3[BCMIm]Br@UiO-66 outperformed the original UiO-66 materials and [BCMIm]Br. P3[BCMIm]Br@UiO-66 retained its good catalytic performance for up to five recycling runs with only a little loss in catalytic activity. Furthermore, several additional coupling reactions were investigated with other epoxides as substrates.