Encapsulated Lewis acidic ionic liquids by halloysite using as efficient catalyst for CO2 conversion

Abstract A type of clay-supported catalysts were developed for conversion of CO2 by encapsulating ZnBr2-based Lewis acidic ionic liquids (ZnBr2/IL) in halloysite (Hal) via a one-step strategy. The Lewis acidic ionic liquid was loaded within enlarged lumens of Hal via acid treatment, and the mesoporous structure was found to benefit for CO2 storage/conversion. The composite ZnBr2/IL@P-Hal was found to have an adsorption capacity (6.43 cm3/g) of CO2 via adsorption/desorption isotherm measurements. The composite ZnBr2/IL@P-Hal showed excellent catalytic performance (TOF value was 1747.7 h−1) for coupling of CO2 with epoxides to produce propylene carbonate under the lack of any cocatalyst. Kinetic investigations indicated the reaction followed an order of one, with respect to catalyst ZnBr2/IL@P-Hal. The overall pathway of CO2 cycloaddition was theoretically validated via DFT calculations. These experimental and computational efforts deepen comprehension of the rational design of clay-based catalysts for CO2 cycloaddition, further elucidated halloysite was a promising support.