Chemical conversion of CO2 into cyclic carbonates using a versatile and efficient all-in-one catalyst integrated with DABCO ionic liquid and MIL-101(Cr)

Abstract

A novel heterogeneous catalyst, MIL-101(Cr)-DABCO IL, with DABCO serving as bridge agent to merge the advantages of ionic liquids (IL) and metal-organic framework (MOF) was prepared and evaluated as catalyst for the synthesis of cyclic carbonates from CO 2 and epoxides. The coordinatively unsaturated Cr(III) nodes in MOF framework function as specific centers to chelate tertiary N atom in DABCO, which offers a bridge that has strong affinity to ensure the active moieties facilely anchored on MOF. Notably, the MIL-101(Cr)-DABCO as an effective catalyst displays exceptional catalytic performance with 88.6% of yield and 99.2% of selectivity at 1.5 MPa and 100 °C for only 40 min, which is urgently required and of positive significance for the environment protection. When the DABCO moiety was further transformed to hydroxyl-functionalized IL, pivotal factors required to activate CO 2 and epoxide, including Lewis acid-basic sites and nucleophile, are combined together in MIL-101(Cr)-DABCO IL. The resultant all-in-one MIL-101(Cr)-DABCO IL catalyst doubles the activity in driving the cycloaddition reaction by comparing with MIL-101(Cr)-DABCO. The highest productivity of cyclic carbonate up to 97.0%, and 99.8% of selectivity are given by MIL-101(Cr)-DABCO IL. Moreover, benefited from the superb coordinative bonding interaction of the well built Cr(III)–N bonds, the MIL-101(Cr)-DABCO IL have excellent recyclability and chemical stability. • DABCO IL was facilely anchored into MIL-101(Cr) through the formation of coordination bonding between DABCO and Cr. • MIL-101(Cr)-DABCO displays exceptional catalytic performance with 88.6% of yield in 40 min. • The MIL-101(Cr)-DABCO IL doubles the activity by comparing with MIL-101(Cr)-DABCO due to its multiple active sites.