Superior Catalytic Performance of Mesoporous Zeolite TS-1 for the Oxidation of Bulky Organic Sulfides
Superior Catalytic Performance of Mesoporous Zeolite TS-1 for the Oxidation of Bulky Organic Sulfides
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DOI：
10.1002/cctc.201300084
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发表时间：
2013-08-01
期刊：
影响因子：
4.5
通讯作者：
Tang, Tiandi
中科院分区：
文献类型：
--
作者：
Kang, Zhenzhen;Fang, Guoyong;Tang, Tiandi
氧化反应是有机合成中一个非常重要的反应。[1]在过去的几十年中，过渡金属配合物，包括钛，钼和钒的配合物，已被发现是用于有机化合物的选择性氧化的高效催化剂，并在有机合成中发挥重要作用。[2]然而，这些均相催化剂具有几个缺点，例如高成本、低稳定性和有限的可重复使用性，这限制了它们在工业应用中的使用。这些问题的解决方案是用高活性多孔固体催化剂代替均相催化剂。众所周知，钛硅酸盐沸石TS-1以及其它含钛沸石如Ti-β、Ti-ZSM-12和Ti-ZSM-48是用于氧化有机化合物的高效催化剂。[3，4]然而，这些沸石催化剂的一个缺点是其骨架中的孔太小而不能被庞大的反应物进入。[5]为了克服这一限制，人们合成了含钛介孔分子筛，如Ti-MCM-41和Ti-SBA-15。[6]不幸的是，由于存在六配位钛物质，这些催化剂显示出相对低的催化活性。[7]近年来，以纳米碳和两亲性有机硅烷为模板剂合成具有结晶骨架的介孔分子筛TS-1的研究取得了巨大的进展。[8]然而，这些中孔沸石的工业应用仍然受到纳米级碳模板的使用中涉及的合成程序的复杂性和两亲性有机硅烷模板的费用的限制。本文中，我们报道了一种通过使用含有季铵基团的介观无规共聚物（RCQA-1）作为模板制备介孔沸石TS-1（MTS-1）的简便且通用的路线（参见S1部分）。2、支持信息）。与无介孔分子筛TS-1相比，MTS-1分子筛对硫化物氧化为亚砜或砜的反应具有优异的催化活性和高度可控的化学选择性。基于催化数据和密度泛函理论（DFT）计算，提出二氧化钛过氧化氢（η2）基团是硫化物氧化成亚砜和砜的活性位点MTS-1的XRD图谱在4-808范围内显示出良好分辨的峰，与丝光沸石骨架反转（MFI）结构一致（参见支持信息，图S2）。图1显示了MTS-1的N2等温线、SEM图像和TEM图像。煅烧的MTS-1的氮等温线在0.45-0.90的相对压力下表现出台阶，其为
Oxidation is a fundamentally important reaction in organic synthesis.[1] Over the past few decades, transition-metal complexes, including those of titanium, molybdenum, and vanadium, have been found to be highly effective catalysts for the selective oxidation of organic compounds and have played important roles in organic synthesis.[2] However, these homogeneous catalysts suffer from several drawbacks, such as high cost, low stability, and limited reusability, which curtail their use in industrial applications. A solution to these problems is to replace the homogeneous catalysts with highly active porous solid catalysts. It is well-known that titanosilicate zeolite TS-1, as well as other titanium-containing zeolites, such as Ti-β, Ti-ZSM-12, and Ti-ZSM-48, are highly efficient catalysts for the oxidation of organic compounds.[3, 4] However, one disadvantage of these zeolite catalysts is that the pores in their frameworks are too small to be accessed by bulky reactants.[5] To overcome this limitation, Ti-containing mesoporous molecular sieves, such as Ti-MCM-41 and Ti-SBA-15, have been synthesized.[6] Unfortunately, those catalysts have shown relatively low catalytic activities, owing to the presence of hexa-coordinated titanium species.[7] In recent years, tremendous efforts have been made to synthesize mesoporous zeolite TS-1 with a crystalline framework by using nanosized carbon and amphiphilic organosilanes as templates.[8] However, the industrial application of these mesoporous zeolites is still limited by the complexity of the synthetic procedures that are involved in the use of nanosized carbon templates and by the expense of amphiphilic organosilane templates. Herein, we report a facile and universal route to mesoporous zeolite TS-1 (MTS-1) by using a mesoscale random copolymer that contains quaternary ammonium groups (RCQA-1) as a template (see section S1. 2 in the Supporting Information). Compared with mesoporous-free TS-1, the MTS-1 zeolite shows extraordinarily catalytic activity and highly controllable chemoselectivity for the oxidation of sulfides into sulfoxides or sulfones. Based on the catalytic data and density functional theory (DFT) calculations, the TiÀhydroperoxo (η2) groups are proposed to be the active sites for the oxidation of sulfides into sulfoxides and sulfones.The XRD pattern of MTS-1 exhibits well-resolved peaks within the range 4–808, consistent with a mordenite framework inverted (MFI) structure (see the Supporting Information, Figure S2). Figure 1 shows the N2 isotherm, a SEM image, and a TEM image of MTS-1. The nitrogen isotherm of calcined MTS-1 exhibits a step at a relative pressure of 0.45–0.90, which is