Wang J, Chen Z, Yu Y, Tang Z, Shen K, Wang R, Liu H, Huang X, Liu Y
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University North Zhongshan Rd 3663 Shanghai 200062 P. R. China
RSC Adv. 2019 Nov 20;9(65):37801-37808. doi: 10.1039/c9ra07893b. eCollection 2019 Nov 19.
Hollow core-shell structured TS-1@S-1 zeolite (HCS-TS) was prepared successfully for the first time, which exhibited excellent activity in the epoxidation of alkenes. Combining TEM, UV-vis, UV-Raman, pyridine-IR, solid-state MAS NMR, XPS and so on characterization, the improvement in the catalytic performance of hollow core-shell structured TS-1@S-1 zeolite was credited to the newly formed superior active sites: defective Ti(OSi)(OH) species in HCS-TS and six-coordinated titanium active species in uncalcined HCS-TS (HCS-TS). Interestingly, these two different titanium active species in the samples could be constructed through calcination or not in the same synthesis process. A possible formation mechanism was investigated in detail; it indicated that the hollowing treatment of TS-1 in the first step was conducive to the construction of the new superior active sites in the samples, and there was a synergistic effect on the formation of these active sites between TPAOH and TEOS in the second step of the synthesis process. This strategy is feasible to enhance the catalytic performance of TS-1, and is suitable for the synthesis of TS-1 on an industrial scale.
首次成功制备了中空核壳结构的TS-1@S-1沸石（HCS-TS），其在烯烃环氧化反应中表现出优异的活性。结合透射电子显微镜（TEM）、紫外可见光谱（UV-vis）、紫外拉曼光谱（UV-Raman）、吡啶红外光谱（pyridine-IR）、固体高分辨核磁共振（solid-state MAS NMR）、X射线光电子能谱（XPS）等表征手段，中空核壳结构的TS-1@S-1沸石催化性能的提高归因于新形成的优异活性位点：HCS-TS中缺陷的Ti(OSi)(OH)物种和未煅烧的HCS-TS（HCS-TS）中的六配位钛活性物种。有趣的是，样品中的这两种不同的钛活性物种可以在同一合成过程中通过煅烧与否来构建。详细研究了一种可能的形成机制；结果表明，第一步对TS-1进行中空处理有利于样品中新的优异活性位点的构建，并且在合成过程的第二步中，四丙基氢氧化铵（TPAOH）和正硅酸乙酯（TEOS）之间对这些活性位点的形成存在协同效应。该策略对于提高TS-1的催化性能是可行的，并且适用于工业规模的TS-1合成。
