Recyclable and Magnetically Functionalized Metal–Organic Framework Catalyst: IL/Fe3O4@HKUST-1 for the Cycloaddition Reaction of CO2 with Epoxides

A recyclable and magnetic nanocomposite catalyst (IL/Fe3O4@HKUST-1) was synthesized via grafting ionic liquid (IL) [AEMIm]BF4 into magnetically functionalized metal–organic framework Fe3O4@HKUST-1 in a water–ethanol media. The properties of IL/Fe3O4@HKUST-1 were fully characterized by powder X-ray diffraction, electron microscopy, Fourier-transform infrared spectroscopy, nitrogen adsorption–desorption, density-functional theory, and a magnetic property measurement system. IL/Fe3O4@HKUST-1 showed high activity in the solvent-free cycloaddition of CO2 with epoxides under mild conditions. Furthermore, the catalyst can be easily separated from the reaction mixture, and the recycled catalyst maintained high performance for several cycles. The synergistic effect of the Lewis acid and base sites in IL/Fe3O4@HKUST-1 contributes to its greater reactivity than individual IL or HKUST-1.