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以正硅酸乙酯为硅源,正十六胺为模板剂,乙醇和水为溶剂,采用水热合成法制备了纯硅HMS介孔材料.以TiCl4为钛源,采用气相接枝技术将Ti物种引入到HMS的骨架中,制得Ti/HMS催化剂;以六甲基二硅氮烷为硅烷化试剂,采用液相接枝技术,将甲基接枝到Ti/HMS催化剂表面,以提高催化剂的疏水性.采用XRD、N2吸附、TEM、UV-Vis和FT-IR等技术表征研究了催化剂的结构、表面化学组成及疏水性;以过氧化氢异丙苯为氧化剂,分别在淤浆床及固定床反应器中,研究了Ti/HMS催化剂对丙烯的催化环氧化性能及稳定性.研究结果表明,所制备的Ti/HMS催化剂具有典型的六方介孔结构特征,且钛物种主要以四配位的活性物种形式存在于骨架中;经硅烷化试剂处理后,催化剂的疏水性得到显著提高;经硅烷化处理后的催化剂对丙烯环氧化具有优异的活性、选择性和稳定性,在2400小时的稳定性实验中,CHP的转化率维持在99.0%以上,环氧丙烷的选择性维持在97.0%以上.
Pure mesoporous HMS mesoporous materials were synthesized by hydrothermal synthesis using tetraethyl orthosilicate as silicon source, n-hexadecylamine as templating agent, ethanol and water as solvent, TiCl4 as titanium source, Ti species into the framework of HMS to prepare Ti / HMS catalyst; hexamethyldisilazane as silylation reagent, the use of liquid grafting technology, the methyl grafted to the Ti / HMS catalyst surface to improve The hydrophobicity of the catalyst was investigated by means of XRD, N2 adsorption, TEM, UV-Vis and FT-IR. The structure, surface chemical composition and hydrophobicity of the catalyst were investigated. Cumene hydroperoxide Bed and fixed bed reactor, the catalytic epoxidation performance and stability of Ti / HMS catalyst were studied.The results show that the prepared Ti / HMS catalyst has typical hexagonal mesoporous structure, and the main species of titanium The four-coordinated active species existed in the framework. After the silylation reagent was treated, the hydrophobicity of the catalyst was significantly improved. The silylated catalyst had excellent activity, selectivity and stability for propylene epoxidation In a 2400 hour stability experiment, CHP turned The rate is maintained above 99.0% and the selectivity to propylene oxide is maintained above 97.0%.