Epoxidation of Styrene Catalyzed by Ion-exchanged NaY Zeolites

Using NaY zeolite(Me-NaY) ion-exchanged with various metal ions as catalysts,the epoxidation of styrene with oxygen as oxidant was investigated.The catalysts were characterized by XRD and BET and the reaction products were qualitatively identified by GC-MS and quantitatively analyzed by GC.The results show that the framework of NaY keeps unchanged after ion exchange,the main products of styrene epoxidation reaction are styrene oxide and benzaldehyde,and Co~(2+)-exchanged zeolite Y exhibites the highest reaction activity.At the same time,various reaction conditions were examined by using Co~(2+)-exchanged zeolite Y as the catalyst.It is found that the viscosity and polarity of the solvent have strong influence on the reaction and the solvent with lower viscosity and weaker polarity is favorable,the conversion of styrene increases while the selectivity of styrene oxide decreases with the increase of the reaction temperature,the reaction reaches equilibrium for 6 h on the whole.Using Co~(2+)-exchanged zeolite Y as the catalyst and dimethyl formamide as the solvent,67.5% of styrene conversion and 48.8% of styrene oxide selectivity are obtained at 1 000 ℃ for 6 h.