Integration of multifunctionalities on ionic liquid-anchored MIL-101(Cr): A robust and efficient heterogeneous catalyst for conversion of CO2 into cyclic carbonates

Abstract

Abstract The rational integration of multiple functional components into a suitable matrix material is a promising strategy for constructing efficient catalysts for specific applications. Herein, a novel Zn-containing imidazolium bromide was facilely anchored onto MIL-101(Cr) (MIL-101(Cr)-(AIm)2ZnBr2) via a coordination bond between the amino group in ionic liquid (IL) moiety and unsaturated Cr3+ center in MOF framework, which catalyzed the efficient synthesis of cyclic carbonates through the cycloaddition of CO2 and epoxides. The as-prepared MIL-101(Cr)-(AIm)2ZnBr2 groups the essential factors that facilitate the superb cycloaddition efficiency, involving: (1) Cr (III) and Zn (II) working as Lewis acid sites for polarizing epoxide; (2) amino groups and ternary N species as Lewis basic sites for activating CO2; (3) Br− anion as nucleophile to accelerate the opening of epoxy ring. Combining the high surface area (1146 m2/g) and numerous open pores, a high up to 97.3% of propylene carbonate yield and 100% of selectivity are achieved. Additionally, benefited from its good chemical stability, the catalyst maintains its high activity even after five successive runs. This work proposes a new strategy for constructing multifunctional catalyst for CO2 conversion by highlighting the synergistic effect enabled by one host.