| Fuel,as an important energy source,has been widely used for supporting the rapid development of industries,such as manufacturing industry,transportation industry and military industry,since the second industrial revolution.While the sulfur compounds in the fuel could not only cause serious environmental problems but also reduce the qualities of people's life.Therefore,it is a crucial issue requiring to be solved on how to remove sulfur compounds in fuel efficiently and quickly to obtain low-sulfur or zero-sulfur fuel.Oxidative desulfurization(ODS)has attracted much attention due to its mild reaction condition,simple reaction process and high sulfur compounds removal efficiency,in which the design and synthesis of effective catalysts for ODS is a research hotspot.Heteropolyacids is a kind of green catalyst,but its disadvantages such as low specific surface area and high solubility in polar solvents limit its further development in ODS.It is effective to enhance the catalytic performances of heteropolyacids-type catalysts through immobilizing and modifying them.Ionic liquids,as a green solvent,has a good extractive capability on sulfur compounds in the fuel but it would be a high cost if using it only as an extractant.Immobilizing ionic liquids on the catalyst by polymerization could not only maintains its extractive desulfurization activity but also prevents its loss,so the application of poly(ionic liquid)s catalyst for ODS has been a newly-developing research topic.Based on the above thoughts,two series of SiO2@poly(ionic liquid)s-heteropolyacids catalysts with core-shell structure were designed and prepared in this dissertation for ODS processing.The main contents were listed as below:1.Two types of ODS catalysts with core-shell structure,microporous SiO2@poly(1-vinylimidazole)-PMoW(abbreviated as mi-SPIP)and microporous SiO2@poly(4-vinylpyridine)-PMoW(abbreviated as mi-SPVP),were prepared through immobilization of 1-vinylimidazole/4-vinylpyridine and heteropolyacids(H3PMo6W6O40,abbreviated as PMoW)on the surface of microporous SiO2 by free radical polymerization and impregnation method,respectively.The structures,morphologies and physical-chemical properties of the synthesized catalysts were characterized by FT-IR,UV-Vis,N2 adsorption-desorption,ICP,SEM and TEM.Then the catalysts were used for removing dibenzothiophene in the model fuel.The results showed that mi-SPIP and mi-SPVP could achieve dibenzothiophene removal efficiency at99.37 % and 98.61 %,respectively.Also,these two catalysts could maintain their high dibenzothiophene removal efficiency over 93 % after 10 recycles.It is the unique core-shell structure of mi-SPIP/mi-SPVP that enables PMoW to be located on the shell part of the catalysts,exposing more catalytic active sites and reducing the mass transfer resistance between sulfur compounds and the catalysts as low as possible.Therefore,these two catalysts could show excellent oxidative desulfurization performances.2.Three types of ODS catalysts with core-shell structure,mesoporous SiO2@poly(1-vinylimidazole)-PMoW(abbreviated as C0-me SPIP),mesoporous SiO2@poly(1-vinyl-3-butylimidazole)-PMoW(abbreviated as C2-me SPIP)and mesoporous SiO2@poly(1-vinyl-3-ethylimidazole)-PMoW(abbreviated as C4-me SPIP),were prepared through immobilization of1-vinylimidazole/1-vinyl-3-ethylimidazole/1-vinyl-3-butylimidazole and PMoW on the surface of mesoporous SiO2 by free radical polymerization and impregnation method,respectively.The structures,morphologies and physical-chemical properties of the synthesized catalysts were characterized by FT-IR,UV-Vis,N2 adsorption-desorption,ICP,SEM and TEM.Then the catalysts were used for removing four types of thiophenic sulfur compounds in the model fuel.The results revealed that the sulfur compounds removal efficiency of 3 catalysts from high to low is: me-C2 SPIP > me-C0 SPIP > me-C4 SPIP.Meanwhile,it could be known that the size of pores and particles of SiO2 also have impacts on the desulfurization abilities of prepared catalysts when comparing the catalytic abilities of me-C0 SPIP and mi-SPIP. |
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