Ti-Beta分子筛的控制合成及高效催化环己烯环氧化

构建了以H₂O₂为氧化剂催化环己烯合成环氧环己烷的高效、 绿色催化反应体系. 在不加入铝源的情况下, 以四乙基氢氧化铵(TEAOH)为模板剂, 通过改进的干胶转化法控制H₂O/SiO₂摩尔比为1.5合成出Ti-Beta分子筛. 实验结果表明, 适宜的酸碱性、 含水量以及模板剂用量显著影响分子筛的结晶度, 同时影响晶粒尺寸和晶粒尺寸的均一性. 通过对Ti-Beta分子筛原粉进行焙烧处理制得Ti-Beta分子筛催化剂, 再通过对反应溶剂、 反应温度和反应时间的筛选和优化, 获得最优催化反应条件, 在该条件下, 环己烯转化率可达33.5%, 环氧环己烷选择性可达99.6%. 实验结果表明该催化剂是一种高效的多相催化剂.

Controllable Synthesis of Ti-Beta Zeolite and Efficiently Catalytic Epoxidation of Cyclohexene†

The construction of a green catalytic reaction system with characteristic of high efficiency for the synthesis of epoxycyclohexane by catalytic epoxidation of cyclohexene with H₂O₂ was focused. We succeeded in synthesizing Ti-Beta zeolites in the absence of Al by the dry-gel conversion method using tetraethylammonium hydroxide(TEAOH) as the structure directing agent with n(H₂O)/n(Si) of about 1.5. We found that the crystallization, the uniformity of crystal and size of Ti-Beta were significantly affected by proper acidity and basicity, the amount of water and template dosage. Then, highly efficient Ti-Beta catalyst was prepared by calcination treatment of the raw powder. Under the optimal catalytic reaction conditions, the cyclohexene conversion of 33.5% and the epoxidation selectivity of 99.6% were achieved. The results indicate that Ti-Beta is an excellent heterogeneous catalyst.