| Ti-HSZ（Ti-containing hollownest-structured zeolite）is a new type of titanosilicate zeolite with hollow nest morphology.It exhibits excellent catalytic activity in epoxidation of macrocyclic monoolefin molecules,with the advantages of“green synthesis,green application,excellent performance”,which breaks through the bottleneck of low epoxidation efficiency of bulky cycloalkenes catalyzed by titanosilicate zeolite for a long time.It is worth noting that,unlike the“dynamic”agitation synthesis method that people usually use,there is no stirring device such as stirring blade（rod,paddle）in the reactor for synthesizing Ti-HSZ material,and no stirring rod is placed.The HSZ material is completely self-assembled under rotating hydrothermal conditions.Although the research on the crystallization mechanism of zeolite molecular sieve under static or dynamic stirring conditions has been extensively studied,the research on the crystallization mechanism under“rotation”conditions has not been reported.The Ti-MWW zeolite was synthesized for the first time by conventional static crystallization mode,and its similar“flower”morphology is completely different from the hollow nest morphology of Ti-HSZ material.Through the comparative study of two kinds of hydrothermal synthesis routes of“rotation”and“static”,it is found that the rotational crystallization mode plays a vital role in the formation of Ti-HSZ materials;Through the comparative study system,the crystallization process,crystallization regularity and physicochemical properties of the original molecular sieves in the two crystallization modes were investigated,and the one-step hydrothermal synthesis crystallization process and mechanism of Ti-HSZ materials were also discussed.Secondly,various catalytic materials were obtained by post-treatment of the prepared precursors in treatment methods（such as acid-treatment,calcination,acid-treatment/calcination）,and their physical and chemical properties were tested and characterized,and the influence of crystallization mode on material synthesis was discussed.These catalytic materials were applied in the test of catalytic performance for epoxidation of macromolecular cyclolefins（>five-membered rings）using hydrogen peroxide as oxidant,and the structure-activity relationship of the catalyst was systematically studied.Finally,Ti/Al-HSZ catalytic materials with high exposive titanium were synthesized by dealuminization and recrystallization of Al-HSZ.The effects of various dealuminization and recrystallization conditions（such as nitric acid concentration,secondary crystallization time,etc.）on the physicochemical properties of Ti/Al-HSZ materials and their catalytic properties for epoxidation of macrocyclic olefins were systematically investigated.Compared with the one-step synthesized Ti-HSZ material,the recrystallization of Ti/Al-HSZ material not only greatly improved the utilization of titanium source（TBOT）,but also significantly increased the Tiopen ratio of Ti/Al-HSZ material,thereby improving its catalytic activity for epoxidation of bulky cycloalkenes. |
