Chiral Molecular Sieve and Molecular sieves with special structure

Chiral Molecular Sieve

At present, highly selective reactions, especially asymmetric catalytic synthesis reactions have become one of the focuses of research, and have important application prospects in the synthesis industry such as pharmaceuticals, development of crops, agricultural chemicals, and food additives. Zeolite molecular sieves are used as catalysts When materials undergo asymmetric synthesis reactions, molecular sieves are often used as the main body, and complexes with asymmetric structures and metal organics are immobilized to form new chiral catalysts. However, the chiral catalysts prepared in this way can only be obtained by Bridge bonds or auxiliary reagents introduce chirality, so the stability and catalytic life of the catalyst have always hindered its further industrial development and application. If molecular sieve materials with chiral structures can be synthesized, their stability problems may be solved. The chiral b zeolite was synthesized by adding a chiral structure directing agent, but only 5% enantioselectivity was obtained by photoactivity experiments. 7. Recently, two chiral germanium-silicon molecular sieves, SU-15 and SU-32, have been synthesized. Although these materials have not yet been used, they have established a good research foundation for the realization of chiral catalysis of molecular sieves.

Molecular sieves with special structure

MWW type zeolite molecular sieve is a new type of layered high silica zeolite with dual-channel system, family members include MCM-22, MCM-49, MCM-36, MCM-56, PSH-3, SSZ-25, ERB- 1, ITQ-1, ITQ-2, EMM-10, EMM-12 and EMM-13, etc., its layers include two-dimensional, sinusoidal and crossed ten-membered ring elliptical channel systems, and twelve-membered ring hyperloops between layers. Cage, unlike traditional zeolite molecular sieves, has large pores on its surface. Therefore, it is used in olefin isomerization, aromatic alkylation to ethylbenzene or cumene, catalytic cracking and hydrocracking, toluene disproportionation, and aromatization In the past two decades, the research, development and application of MWW molecular sieves have always been the focus of attention in the field of molecular sieves. Mobil has launched Mobil-Badger liquid phase alkane based on MWW zeolite catalysts. The new technology for the production of cumene by radicalization, the catalytic process not only has a low reaction temperature, but also has a long catalyst life and high selectivity, and the cumene selectivity reaches more than 99.99%. 5 and β molecular sieves for the manufacture of cumene. In addition, MWW-type zeolite molecular sieve catalysts have also been used in the industrial production of ethylbenzene. EU-1 molecular sieve (EUO) contains ten-membered ring straight channels and twelve-membered Ring side pocket (Side Pocket) structure, this special structure makes it show higher activity and selectivity in xylene isomerization reaction, so it has application development prospects. Medium pore zeolite with non-intersecting, one-dimensional channels , such as TON, MTT, EUO and AEL, etc., as bifunctional alkane hydroisomerization catalysts, have higher yield and product selectivity than traditional ZSM-5, ZSM-11 or beta zeolite, and thus have a certain Application development prospects.