Catalytic epoxidation of alkenes with 30% H2O2 over Mn2+-exchanged zeolites

The Mn2+-exchanged zeolites Mn-Y, Mn-beta, Mn-A and Mn-ZSM-5 were prepared and used as heterogeneous catalysts for the liquid phase epoxidation of alkenes with aqueous hydrogen peroxide (30% H2O2) at 273–298 K in the NaHCO3 buffer system. The structures of catalysts were characterized by powder X-ray diffraction (XRD), UV–vis, ICP, BET and IR techniques. Mn-beta and Mn-Y exhibited the best recyclable activity for the epoxidation of styrene to achieve styrene conversions higher than 96.0 and 98.5 mol%, respectively. Mn-beta showed higher activity for cyclohexene and norbornene but lower activity for α-methylstyrene, cinnamyl chloride, indene, cyclooctene and α-pinene than Mn-Y, which could be correlated with the difference of their pore sizes. However, these catalysts did not show any activity for the epoxidation of 1-octene with H2O2, possibly due to low electron density of double bonds of linear terminal alkenes.

Mn2+-exchanged zeolites Mn-beta, Mn-Y, Mn-ZSM-5, and Mn-A efficiently catalyzed the epoxidation of alkenes with 30% H2O2, in which Mn-beta and Mn-Y exhibited highly recyclable activity.Figure optionsDownload high-quality image (38 K)Download as PowerPoint slide