Efficient air epoxidation of cycloalkenes over bimetal-organic framework ZnCo-MOF materials

Abstract

To date, it was difficult to develop catalytic systems for activating O2 in the absence of initiator and sacrificial co-reductant for high-efficiency epoxidation of olefins under mild conditions. Herein, different compositions of ZnCo-MOF have been prepared via a dry-gel crystallization method, which were used to catalyze the epoxidation of α-pinene with air at 90 °C. Zn0.1Co1-MOF-D2-24 performed the best catalysis activity to give 95.5 % α-pinene conversion and 96.7 % epoxide selectivity. The epoxidation results showed that Zn and Co could effectively activate air to epoxidize α-pinene in high efficiency. This bimetal catalytic effect was assigned to the contribution of interacted lattice Zn and Co ions embedded into crystalline MOF framework with similar electronic structure and ion radius, which avoided the use of organic peroxide initiators and other co-reducing agents. Under anhydrous conditions, Zn0.1Co1-MOF-D2-24 showed stable catalytic activity in the epoxidation of α-pinene with air by at least six recycles.