Study On The Organic Base Modification Of TS-1 And Its Catalytic Synthesis Of ECH

The TS-1/H2O2 catalytic system is a typical green catalytic oxidation chemical technology.It is an effective way to improve the catalytic performance of titanosilicate zeolite from the aspects of diffusion,adsorption and desorption,Ti active centers,and reactive intermediates.The construction of Ti species with different coordination states is the most fundamental of the above methods.Besides,due to the unique pore structure and excellent diffusion property,core-shell structure molecular sieves have attracted great attention in the field of catalytic oxidation.Therefore,this paper used the organic base tetrpropylammonium hydroxide(TPAOH)and piperidine(PI)to modify TS-1,and further developed the efficient green synthesis process of epichlorohydrin(ECH).The main results obtained are as follows:1.The hollow core-shell structured TS-1@S-1 molecular sieve(HCS-TS)was synthesized by hydrothermal synthesis of TPAOH treated TS-1(H-TS-1)with tetraethyl silicate(TEOS)and TPAOH.It showed excellent catalytic oxidation performance.The structure analysis shows that when TS-1@S-1 was not clained,it contained hexa-coordinated titanium active centers formed by the coordination of H2O and TPA~+.After calcination,Ti(OSi)3(OH)species was formed.The study of the formation mechanism showed that the H-TS-1 formed by TPAOH treatment of TS-1 was conducive to the construction of different Ti active centers.The synergistic effect of TPAOH and TEOS facilitated the formation of core-shell structure.2.A new method of preparing TS-1~s molecular sieve rich in Ti(OSi)3(OH)species was developed by using PI as the organic base.Compared with the method of preparing TS-1~s molecular sieve with ethylamine(EA)as organic base in the literature,this method can prepare TS-1~s molecular sieve with a higher Ti content,and the Si/Ti ratio(parent)is expanded from 60 to 30.3.The effects of solvent type,molecular sieve type,molecular sieve amount,reaction temperature,n(ALC/H2O2)and other factors on the epoxidation of ALC were systematically studied.The results showed that hollow TS-1(H-TS-1)showed better catalytic performance due to its rich mesoporous content and high hydrophobicity.The effect of the synthesis of ECH was investigated with acetone as solvent and fixed bed reaction mode.The H-TS-1 molecular sieve showed good selectivity and stable running.