Selective Epoxidation of Styrene with Air Catalyzed by Ion-exchanged M-ZSM-5 Catalysts without Reductant, pp. 555-569
Authors: (H.J. Zhan, X.H. Lu1, X.T. Ma, Q.H. Xia - Ministry-of-Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules, Hubei University, Wuhan, China, and others)
Abstract: Catalytic epoxidation of styrene with air over M-ZSM-5 in the absence of any sacrificial reagent (as the reductant) under mild conditions has been developed. Zeolite catalysts such as Y, ZSM-5 and βcould catalyze the epoxidation of styrene with air, in which ZSM-5 exhibited the best activity with 47.4 mol% of substrate conversion and 61.8% of selectivity to epoxide. Different transition metal-containing ZSM-5 samples, such as Co-ZSM-5, Fe-ZSM-5, Mn-ZSM-5, Ni-ZSM-5, Cu-ZSM-5 and Cr-ZSM-5, have been prepared through an ion-exchange route, and used as the catalysts. Only Co-ZSM-5 behaved as a high-efficiency catalyst for the selective oxidation of styrene by molecular oxygen in DMF (N, N-dimethylformamide), which showed uniquely solvent-promoting effects. Under identical conditions Co-ZSM-5 catalyzed 54.2 mol% of the styrene conversion with 68.2% of selectivity to epoxide, superior to other catalysts. The results show that the leaching of Co2+ in small amounts from Co-ZSM-5 did not exert an appreciable negative effect on the activity and selectivity of catalyst, at least in the first several reuses.