Preparation And Catalytic Desulfurizationovermetal Modified Ti-HMS Molecular Sieve

As the sulfur content in diesel fuel standards increasing stringently, Conventional hydrodesulfurization technology can not meet the needs of desulfurization of diesel because of its high desulfurization rate and operating conditions.Therefore,the development of new efficient and more economical desulfurization technology is particularly important.In recent years,the HMS material was widely used in the field of catalytic oxidation desulfurization and made significant progress due to its excellent characteristics. However, the formation mechanism of mesoporous structure, effects of mesoporous structure and properties, as well as modification of material skeleton and application should be investigated further.In this paper, dodecylamine as template synthesized Ti-HMS Molecular Sieve by hydrothermal synthesis method. Ag/Ti-HMS molecular sieve catalyst materials were respectively prepared by three methods respectively,including In situ synthesis method,equal volume impregnation method,ultrasound-assisted impregnation method, and Ti-HMS as a carrier loading the metal of silver. Then, the modified samples were used to catalytic oxidation thiophene and benzothiophene. The effects of preparation methods, preparation conditions and reaction conditions on the desulfurization were emphasis studied. The main content of this paper are as follows:(1)Hexagonal mesoporous silica (HMS) and Titanium-containing hexagonal mesoporous silica (Ti-HMS) were synthesized by using neutral dodecylamine as template and tetraethyl orthosilicate as Si source in neutral solution and at ambient temperature. Ag/Ti-HMS materials were prepared by In situ synthesis method,equal volume impregnation method and ultrasound-assisted impregnation method. XRD, SEM, TEM, UV-Vis, FT-IR characterization techniques were applied to analysize the structure type, physical and chemical properties and surface groups of synthetic molecular sieves.The results showed that HMS and Ti-HMS have the typical mesoporous structure and the structure was kepted well after metal ions were incoporated. The loading metal ion does not enter the molecular sieve framework, but a relatively uniform distribution of the internal and external surfaces of the molecular sieve. The active component dispersion of the Ag/Ti-HMS prepared by ultrasound-assisted impregnation methodis best.(2)Thiophene and benzothiophene were dissolved in n-octane, respectively, formulated as the model of a certain concentration of oil. Ag/Ti-HMS, as catalysts, H2O2as oxidant, emphasis on the study of the molecular sieve removal of the model oil thiophene and benzothiophene. The experiments showed that Ag/Ti-HMS molecular sieves prepared by ultrasound-assisted impregnation method have a higher catalytic activity in the removal of thiophene. Catalytic desulfurization rate of Ag/Ti-HMS Molecular Sieve was highest when n(Si)/n(Ag)=40.The optimal reaction temperature was60℃when oxidative desulfurization of thiophene using the prepared Ag/Ti-HMS samples as catalysts.