Preparation Of Superparamagnetic Supported Heteropolyacid And Application In The Alkylation Of Thiophene And1-Octene

In the current technology of gasoline desulfurization, the alkylation of sulfur compounds with olefins (OATS) which is operated in mild conditions, be nice to environment and doesn’t decrease too much octane number, is considered to be an attractive way. Thiophene and its derivative are the main source of sulfur in FCC gasoline, so the research of alkylation catalyst of thiophene is important to develop the technology of gasoline desulfurization. On the other hand, it is a quite efficient way to prepare magnetic catalyst to separate the catalyst particles from liquid phase. The magnetic composite materials are wildly used in the area of catalysis, magnetic fluid, biological medicine and bioseparation. In our paper, the structure and catalytic activity of supperparamagnetic heteropolyacid were discussed.Superparamagnetic supported catalyst, were prepared by loading H3PW12O40(HPW) onto nanoparticles y-Fe2O3through incipient wetness impregnation method. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infra-red (FT-IR), thermo gravimetric analysis (TG), N2-adsorption and vibrating sample magnetometer (VSM). The physicochemical characterization reveals that y-Fe2O3could be accommodated to immobilize and disperse HPW. Moreover, possessing high magnetization of26.1emu/g and with mesoporous structure with the surface area of35.9m2/g,40wt%HPW loading catalyst is considered to be the proper catalyst for OATS and can be separated in an external magnetic field. In addition, catalytic activity was also investigated in the model alkylation reaction of thiophene with1-octene, and the conversion of thiophene is up to46%at160℃for3h over40wt%HPW/y-Fe2O3. The reusability of catalyst was also researched. After it has been used6times, the conversion of thophene is reduced to28.2%and keeps its property of superparamagnetism with the magnetization of25.2emu/g.In order to increase the activity and magnetism of catalyst, SiO2@Fe3O4nanocomposite used as catalyst support, was prepared via modified Stober method. In the preparation process of SiO2@Fe3O4, the dosages of tetraethoxysilane (TEOS) and cetyl trimethylammonium bromide (CTAB) are crucial to the structure and pattern of SiO2@Fe3O4. The optimum dosages of TEOS and CTAB are3mL and1.5g, respectively. The prepared SiO2@Fe3O4under such conditions is mesoporous material with the surface area of561.2m2/g, possessing high magnetization of45.7emu/g.HPW/SiO2@Fe3O4were prepared by loading HPW onto prepared SiO2@Fe3O4through a wet impregnation method. The catalysts were characterized by XRD, FT-IR, N2-adsorption and VSM. The physicochemical characterization revealed that SiO2@Fe3O4could accommodate to immobilize and disperse HPW. Moreover, possessing high magnetization of30.7emu/g and mesoporous structure with the surface area of303.6m2/g,40wt%HPW loading catalyst is considered to be the proper catalyst for olefinic alkylation of thiophenic sulfur (OATS) and can be separated in an external field. In addition, catalytic activity was also investigated in the model alkylation reaction of thiophene with1-octene, and the conversion of thiophene was up to85.5%after2h at160℃. After it has been used8times, the conversion of thophene is reduced to47.2%and keeps its property of superparamagnetism with the magnetization of30.1emu/g.