Titanium Silicalite-1 Catalyzed Epoxidation Of 1-hexene To 1,2-epoxyhexane

1,2-Epoxyhexane is a kind of important fine chemical intermediate.With active epoxy groups at the terminal position,it can react with many organic compounds to produce chiral compounds with different structures,so it is widely applied in the pharmaceuticals,textile,surfactant,pesticides,etc.However,the current preparation technologies of the epoxy compound with olefins such as chlorohydrination process,Halcon process?indirect oxidation?and peracids process result in serious environmental pollution,equipment corrosion and other potential dangers.Therefore,it is needed to develop a new environmentally friendly process for the olefin epoxidation.In recent years,titanium silicalite-1?TS-1?has attracted much attention for its excellent catalytic oxidation performances with the features of fewer byproducts,high selectivities,mild reaction conditions with dilute H₂O₂ as oxidant and environment benign.In this work,TS-1 powder was hydrothermally synthesized using tetrapropylammonium hydroxide?TPAOH?as the template,tetraethyl orthosilicate?TEOS?and tetrabutyl orthotitanate?TBOT?as Si source and Ti source,respectively.Then,the synthesized TS-1 was treated with TPAOH solution to improve its catalytic properties with the conditions,including treatment concentrations,treatment time and treatment temperatures,were optimized.The treated TS-1 samples were characterized by XRD,FT-IR,UV-Vis,SEM,TEM,ICP and BET and studied in the 1-hexene epoxidation.The results indicated that TPAOH treatment did not destroy the MFI structure of TS-1,but mesopores were generated inside the TS-1 samples.With the increase of the TPAOH concentrations,the treatment temperatures and the treatment time,the mesopores inside TS-1 samples became larger and larger.However,the amount of the framework Ti decreased gradually.Due to the formation of the mesopores inside TS-1 samples,reactants and productions are easier to diffuse,so the catalytic properties of the TS-1 treated by TPAOH were improved with both the conversions of 1-hexene and H₂O₂ and the selectivities of the epoxide increased.