Dimension and shape controllable ZIFs for highly-efficient chemical fixation of CO2 without solvent and co-catalyst

The cycloaddition of CO2 with epoxides is an important strategy to reach the goal of carbon neutral, at the same time high-value-added products can be obtained. The integration of Lewis acidic and alkaline sites makes ZIFs potential catalysts for the CO2 cycloaddition. Herein, through simply adjusting the water proportion in the synthesis solvent, a series of ZIF materials were prepared and applied in the CO2 cycloaddition. The transitional ZIF-(80)-Co combines the advantages of two-dimensional and three-dimensional ZIFs, namely the two-dimensional morphology, well-developed porous structures, higher CO2 adsorption capacity, and rich acidic/ alkaline sites. The outstanding microstructures and surface properties of ZIF-(80)-Co contribute to its superior catalytic performance for the CO2 cycloaddition, and an epichlorohydrin (ECH) conversion of 96.9 % and a cyclic carbonate selectivity of 98 % are achieved without solvent and co-catalyst. Importantly, the cycloaddition of CO2 with ECH over ZIF-(80)-Co is faster than most of the reported ZIFs in literature. Furthermore, ZIF-(80)-Co also exhibits excellent catalytic performance in the CO2 cycloaddition with epoxy butane, allyl glycidyl ether, cyclohexene oxide and styrene oxide.