Preparation Of Attapulgite-supported Titanium Silicon Molecular Sieve And Its Application In The Synthesis Of Epichlorohydrin

Propylene chloride is directly oxidized by H₂O₂ to prepare epichlorohydrin（ECH）,which is a new method for preparing ECH,which greatly reduces the production of pollutants,and has the advantages of mild reaction conditions and short reaction time.Although the chloropropylene epoxidation method meets the requirements of green development,molecular sieves are difficult to separate from the product,so that it cannot be commercialized.In this paper,nano-scale titanium silica molecular sieve（TS-1）was prepared,supported by attapulgite,to catalyze the preparation reaction of ECH,and the synthesis conditions were compared.The main research contents are as follows:1.The seed-assisted method is used to prepare nano-scale TS-1 molecular sieves.At the same time,relatively cheap tetrapropyl ammonium bromide（TPABr）is used to replace expensive tetrapropyl ammonium hydroxide（TPAOH）.The conditions of butylamine,diethylamine and ammonia were compared with the addition amount of crystal seeds.The self-made TS-1 molecular sieve was analyzed by XRD,FI-TR,UV-Vis,SEM and BET characterization methods.The results show that when n-butylamine is an alkali source,it can promote the template and orientation of the template agent.The synthesized TS-1 molecular sieve has a better crystal structure and a higher skeleton titanium content.When the addition amount of crystal seeds is 7%,the size of the crystal reaches 200 nm,and the crystallization effect is relatively good.2.Attapulgite supported TS-1 molecular sieve was prepared,and the loading mode and loading capacity were investigated.The prepared attapulgite supported TS-1 molecular sieve was characterized by FI-TR,UV-Vis,SEM,BET and TG-DSC characterization methods.The results show that the attapulgite prepared by the calcination and loading method supports TS-1 with higher titanium content and better catalytic performance.The pore size of the supported catalyst is increased,and it increases with the increase of the loading.3.In the epoxidation of propylene chloride,under the same synthesis conditions,the catalytic performance of micron-sized TS-1 molecular sieves,nano-sized TS-1molecular sieves and attapulgite-loaded TS-1 molecular sieves（loading 50%）were investigated.The results show that the catalytic performance of nano-TS-1molecular sieve is better,the yield of ECH is 91.8%.The second is the attapulgite supported TS-1 molecular sieve,the yield of ECH is 73.6%.Under these conditions,the attapulgite loaded with TS-1 molecular sieve（loading amount is 50%）was used continuously for 5 times,and the yield of ECH was still 60.7%,it shows that attapulgite can be used as a good carrier for TS-1 molecular sieve,which provides a feasible method for the industrial application of TS-1 molecular sieve.