Ti掺杂苯基桥连有序介孔有机硅的制备及其催化烯烃环氧化

发布时间：2018-05-20 17:34

  本文选题：钛 + 周期性介孔有机硅材料　； 参考：《湘潭大学》2017年硕士论文

【摘要】：环氧丙烷是重要的有机中间体,广泛应用于石油化工、医药、电子工业及高分子材料等领域。烯烃环氧化反应是制备环氧化合物的重要途径,现有的生产方法包括氯醇法、共氧化法和双氧水氧化法。高选择性易回收催化剂的开发仍然是建立高效烯烃环氧化反应体系的关键。本论文在课题组前期研究工作的基础上,进一步优化了钛掺杂苯基桥连有序介孔有机硅(Ti-PMOs)的制备条件,在环己烯环氧化指针反应中考察其催化性能和重复使用性能,继而将Ti-PMOs应用于叔丁基过氧化氢为氧源的丙烯环氧化反应体系,优化工艺条件,探寻构效关系,为丙烯环氧化新催化体系的开发提供研究积累。首先,采用一步水热合成法在酸性条件下制备出Ti-PMOs催化剂,并对其进行硅烷化改性。为了匹配钛源钛酸四丁酯(TBOT)和硅源的水解速率,考察了水解抑制剂种类和用量对Ti-PMOs催化剂结构的影响,通过FT-IR、UV-Vis、N2物理吸附等手段对催化剂进行表征。结果表明:相对于乙酰丙酮,以H2O2为水解抑制剂,且n(TBOT):n(H2O2)=0.02:12时,Ti-PMOs催化剂的活性钛含量最高。将该催化剂应用于以TBHP为氧源,烯过比为2:1的环己烯环氧化反应,在80℃下反应5h,获得了37.4%的环己烯转化率,100%的环氧环己烷选择性。其次,为探索Ti-PMOs催化剂的重复使用性能,采用溶剂洗涤、抽滤等步骤对催化剂进行了两次回收。将回收后的催化剂进行一系列表征,结果表明:经一次回收后的催化剂骨架中的活性钛流失明显,而经二次回收后其活性钛含量几乎不变。将回收的催化剂应用于环己烯环氧化指针反应中,结果为经一次和二次回收的催化剂环己烯转化率分别下降至25.9%和24.8%,环氧环己烷的选择性分别下降至97.7%和93.0%,生成少量副产物环己酮和环己二酮。最后,为进一步明确催化剂的结构特征,选用NH3-TPD、显微激光拉曼光谱对比了Ti-SBA-15、Ti-PMOs及Ti-PMOs-S(硅烷化)中钛的存在形式及其分布。同时,将上述催化剂用于以TBHP为氧源的丙烯环氧化反应中,结果表明:有机硅源的加入和硅烷化修饰有利于活性四配位钛的形成,提高了催化剂的活性。以Ti-PMOs-S为催化剂,考察了溶剂种类、反应温度、烯过比、反应时间等因素对丙烯环氧化反应的影响。结果表明:以乙腈为溶剂,烯过摩尔比为6.5:1,在120℃下反应2h时,Ti-PMOs-S催化丙烯环氧化的效果最佳,TBHP的转化率为95.8%,环氧丙烷和叔丁醇的选择性(以TBHP计)分别为78.8%和95.9%。
[Abstract]:Propylene oxide is an important organic intermediate, widely used in petrochemical, pharmaceutical, electronic industry and polymer materials. Epoxidation of olefins is an important way to prepare epoxy compounds. The existing production methods include chlor-alcohol method, co-oxidation method and hydrogen peroxide oxidation method. The development of high selectivity and easy recovery catalyst is still the key to the establishment of high efficiency olefin epoxidation reaction system. The preparation conditions of Ti-PMOs were optimized on the basis of the previous work of our research group. The catalytic properties and reusability of Ti-PMOs were investigated in the epoxidation pointer reaction of cyclohexene. Then Ti-PMOs was applied to propylene epoxidation reaction system with tertiary Ding Ji hydrogen peroxide as oxygen source. The optimization of process conditions and the exploration of structure-activity relationship provided a research accumulation for the development of a new catalytic system for propylene epoxidation. Firstly, Ti-PMOs catalyst was prepared by one step hydrothermal synthesis under acidic conditions and modified by silane. In order to match the hydrolysis rate of titanium tetrabutyl titanate and silicon source, the effects of the type and amount of hydrolysis inhibitor on the structure of Ti-PMOs catalyst were investigated. The catalyst was characterized by FTIR IR UV-VisN 2 physical adsorption. The results show that compared with acetylacetone, H2O2 is used as the hydrolytic inhibitor, and the active titanium content of Ti-PMOs catalyst is the highest in the presence of TBOTH _ 2H _ 2H _ 2O _ 2H _ 2O _ 2H _ 2O _ 2H _ 2O _ 2 = 0.02: 12. The catalyst was applied to epoxidation of cyclohexene at 80 鈩，

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