Hierarchical Co/ZIF-8 as an efficient catalyst for cycloaddition of CO2 and epoxide

An efficient heterogeneous catalyst hierarchical mixed metal Co/ZIF-8 materials were developed for the cycloaddition reaction between CO2 and styrene oxide. The synthesized hierarchical Co/ZIF-8 have been characterized by powder x-ray diffraction, electron microscope, nitrogen adsorption-desorption and thermal gravimetric analysis. The acid-base characteristics of hierarchical Co/ZIF-8 were investigated by NH3 and CO2 adsorption. A maximum cyclic carbonate yield can be obtained over hierarchical 70% Co/ZIF-8 (Co salt content in the substrates mixture is 70%). The styrene oxide conversion reached 96.8% with a selectivity of 97.9% after 8 h of reaction at 0.05 g catalyst dosage, 120 degrees C, 0.70 MPa. The hierarchical Co/ZIF-8 catalyst can be separated by simple centrifugation and reused at least four times with a little loss of catalytic activity. The hierarchical Co/ZIF8 showed enhanced catalytic activity and excellent recyclability and are thus potential heterogeneous catalysts in various catalytic reactions.