Abstract:

Highly stable Co²⁺-NaX catalyst was prepared from Co²⁺-NaX，which was prepared by five times of solid-state ion-exchange，calcination at 500 ℃ for 6 h and then another solid-state ion-exchange. ICP results showed that mass fraction of Co²⁺ in the highly stable Co²⁺-NaX catalyst was 9.13%，which exceeded equilibrium Co²⁺ mass fraction in Co²⁺-NaX prepared by five times of solid-state ion-exchange（8.42%）. The catalysts were characterized by XRD and N₂ adsorption- desorption. The results indicated that the framework of NaX was not destroyed after Co²⁺ exchange，whereas the ordering of NaX decreased with increasing content of Co²⁺ into the zeolite. The optimal conditions were obtained by orthogonal experiments as：styrene 6 mL，catalyst 1.0 g，solvent 48 mL，reaction temperature 80 ℃ and reaction time 6 h. Under such conditions，the average yield of styrene oxide was 39.5%. The catalyst prepared by this method showed higher catalytic activity than Co²⁺-NaX prepared only by five times of solid-state ion-exchange，and the activity was stable after reuse.