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.

沸石骨架中含有四面体钛离子的钛硅酸盐被证明是有吸引力的催化剂，因为它们能够在液相中用清洁的过氧化氢氧化剂氧化多种有机化合物。近二十年来，研究主要集中在两种具有代表性的钛硅酸盐：MFI型TS-1和BEA型Ti-Beta。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，并且其每个Ti位点的比活性仍有很大的提高空间。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。从开发新的烯烃环氧化多相催化工艺的角度来看，迫切需要制备更高效的钛硅酸盐。在这项研究中，我们成功地将Ti掺入具有非常独特的孔结构的MWW沸石中，从而产生了新一代的钛硅酸盐催化剂。使用硼酸作为结晶支持剂的水热合成和通过可逆结构转化的后合成都导致 Ti-MWW 催化剂对烯烃环氧化具有极高的活性。 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，适合大体积反应。还建立了用Ti-Beta开发高活性和选择性催化剂的改性方法。该方法涉及选择性毒害β沸石结构内的酸性位点和氟，但不会对骨架Ti物种的催化性能产生负面影响。含Ti介孔材料Ti-SBA-15和Ti-MSU-G具有通过新型后合成方法和直接水热合成，分别成功制备了较高水热稳定性和抗钛浸出稳定性。