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DESIGN OF HIGHLY EFFICIENT LIQUID-PHASE OXIDATION CATALYSTS OF TITANOSILICATES THROUGH PRECISE CONTROL OF ZEOLITE STRCUTURES

通过精确控制沸石结构设计高效钛硅酸盐液相氧化催化剂

基本信息

批准号：
13305056
负责人：
TATSUMI Takashi
金额：
$ 35.61万
依托单位：
YOKOHAMA NATIONAL UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Titanosilicates containing tetrahedral Ti ions in zeolite framework prove to be attractive catalysts owing to their capability of oxidizing a variety of organic compounds with clean oxidant of hydrogen peroxide in the liquid-phase. In the last two decades, the studies have been focused on two representative titanosilicates, MFI type TS-1 and BEA type Ti-Beta. However, these two titanosilicates have a lot of difficult problems to be tackled. Medium-pore TS-a lacks the ability to oxidize bulky substrates, and there is still a large space to improve its specific activity per Ti site. Ti-Beta, on the other hand, encounters serious disadvantages of easy leaching of Ti active species probably due to its structural stacking faults. From the viewpoint of developing new heterogeneous catalytic processes for alkene epoxidation, it is urgent to prepare more efficient titanosilicates. In this study, we have succeeded in incorporating Ti into MWW zeolite of a very unique pore structure, which leads to a new generation of titanosilicate catalyst. Both hydrothermal synthesis using boric acid as a crystallization-supporting agent and postsynthesis through a reversible structural conversion result in Ti-MWW catalysts extremely active for alkene epoxidation. Ti-MWW is also converted into the catalysts with accessible reaction spaces suitable for bulky reactions by delamination or novel acid treatment.Modification methods for developing highly active and selective catalysts from Ti-Beta have also been established. The methods involve selective poisoning of acid sites and fluorine contained within the structure of Beta zeolite, but without negative influence on the catalytic performance of framework Ti species.Ti-containing mesoporous materials, Ti-SBA-15 and Ti-MSU-G which have higher hydrothermal stability and are stable against Ti leaching have been prepared successfully by novel postsynthesis method and direct hydrothermal synthesis, respectively.

在沸石骨架中含有四面体钛离子的钛硅酸盐催化剂由于其能够在液相中用清洁的氧化剂过氧化氢氧化多种有机化合物而被证明是有吸引力的催化剂。在过去的二十年里，研究主要集中在两种具有代表性的钛硅酸盐，MFI型TS-1和MFI型Ti-β。然而，这两种钛硅酸盐有很多难题需要解决。中孔TS-a缺乏氧化大体积底物的能力，并且仍然存在很大的空间来提高其每个Ti位点的比活性。另一方面，Ti-Beta遇到了Ti活性物质容易浸出的严重缺点，这可能是由于其结构堆垛层错。从开发新型烯烃环氧化多相催化工艺的角度看，制备高效的钛硅酸盐催化剂是当务之急。在这项研究中，我们已经成功地将钛到MWW沸石的一个非常独特的孔结构，这导致了新一代的钛硅酸盐催化剂。水热合成使用硼酸作为结晶支持剂和后合成通过可逆的结构转化的结果在Ti-MWW催化剂非常活跃的烯烃环氧化。Ti-MWW还可以通过分层或新型酸处理转化为具有可进入反应空间的催化剂，以适合大体积反应，并建立了从Ti-Beta开发高活性和选择性催化剂的改性方法。采用后合成法和直接水热合成法分别制备了具有较高水热稳定性和抗钛浸出性能的含钛介孔材料Ti-SBA-15和Ti-MSU-G。