Task-Specific Ionic Liquid Functionalized–MIL–101(Cr) as a Heterogeneous and Efficient Catalyst for the Cycloaddition of CO2 with Epoxides Under Solvent Free Conditions

Abstract

A novel heterogeneous catalyst was synthesized by immobilization of a carboxylic acid- and imidazolium-based ionic liquid on the mesoporous MIL–101(Cr) (MIL–101(Cr)–TSIL) and used to convert abundant, nontoxic, economical and renewable CO2 gas to cyclic carbonates without the need for a cocatalyst or a solvent. The catalyst was characterized in detail by multiple techniques such as XRD, TEM, SEM, EDX, DR-FTIR, solid-state NMR, as well as N2 and CO2 adsorption measurements. The catalytic properties were studied by varying different parameters including amount of catalyst and epoxide, temperature, pressure, and reaction time. Under optimal conditions (100 mg catalyst, 15 mmol epoxide, 2.0 MPa CO2 pressure, 110 °C and 2 h reaction time) various cyclic carbonates were obtained with high yield and selectivity. MIL–101(Cr)–TSIL catalyst displayed good thermal stability and could be reused after simple separation without a significant decrease in its catalytic activity. Due to synergetic effect of the hydrogen b...