CO2+离子交换NaX分子筛催化苯乙烯环氧化

将5次固态交换制备的Co²⁺-NaX于500 ℃焙烧6 h，再进行一次固态交换制备高稳定性催化剂，ICP分析表明其Co²⁺含量为9.13%，高于5次固态交换Co²⁺-NaX的平衡Co²⁺含量（8.42%）。采用XRD、N₂吸附-脱附对催化剂进行表征，结果表明，分子筛离子交换后其骨架结构没有受到破坏，然而随交换进入分子筛Co²⁺含量增多，其有序性下降越明显。通过正交实验对该催化剂催化苯乙烯环氧化进行考察，确定了优化的反应条件：苯乙烯用量6 mL，催化剂1.0 g，溶剂48 mL，反应温度80 ℃，反应时间6 h。在此条件下，环氧苯乙烷平均收率为39.5%。采用该法制备催化剂其活性能够进一步提高，且重复使用活性保持不变。

Epoxidation of styrene catalyzed by Co2+-exchanged NaX zeolite

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.