| With more and more stringent regulatory constraints, it is a trend to achieve little-to-no sulfur diesel as SOX emission has brought forth great negative problems to environment. In the conventional process, hydrodesulfurization is used to remove thiols, sulfides and disulfides. However, it is difficult to remove some sulfur compounds such as dibenzothiophene and its alkyl-substitute derivatives owing to stereo hindrance, which lead to high sulfur content in diesel. Therefore, alternative deep desulfurization technologies have been attracted worldwide attention. Deep desulfurization of diesel containing organic sulfur compounds under mild situations has always been a rather vital research subject in these years, especially the oxidative desulfurization with the green oxidants such as hydrogen peroxide.In this topic, a simple liquid-liquid extraction and catalytic oxidative desulfurization (ECODS) system composed of catalyst, 30%(wt.) H2O2 and ionic liquid has been found suitable for the deep removal of dibenzothiophene in simulated diesel. The sulfur-containing compounds such as benzothiophene, dibenzothiophene and 4,6-dimethyldibenzo-thiophene in simulated diesel were first extracted into ionic liquid phase and oxidized to more polarity sulfones by hydrogen peroxide. The sulfone accumulated in IL and could be easily reclaimed from IL by centrifugation., achieving deep desulfurization of diesel. The research content of this dissertation was following.Six ionic liquids such as 1-butyl-3-methylimidazolium tetrafluoro-borate [Bmim]BF4,1-n-octyl-3-methylimidazolium tetrafluoroborate ([0-mim]BF4), 1-butyl-3-methyl-imidazolium hexafluorophosphate ([Bmim]-PF6), l-n-octyl-3-methylimidazolium hexafluorophosphate ([0mim]PF6), l-butyl-3-methylimidazolium trifluoroacetate ([Bmim]TA) and 1-octyl-3-methylimidazolium trifluoroacetate ([0mim]TA) were synthesized and characterized.A series of simple molybdic compounds catalyzed deep desulfurization of diesel in ionic liquids was studied. It was found that molybdic compounds such as Na2MoO4·2H2O, H2MoO4, H3PMo12040·13H2O, (NH4)6Mo7O24·4H2O, (NH4)3PMo12O40·7JH2O and Na3PM12O40·7H2O as catalysts give high sulfur removal in [Bmim]BF4 extraction and catalytic oxidative desulfurization system. In the case of the system containing simulated diesel (DBT), H2O2, Na2MoO4·2H2O and [Bmim]-BF4, extraction and catalytic oxidation increased the sulfur removal to 99.0%, which was remarkably superior to mere solvent extraction with IL (13.6%) or catalytic oxidation without IL (4.1%). The desulfurization system could be recycled five times with slight decrease in activity. The process and mechanism of ECODS was deeply studied by UV-Vis and IR.A series of simple tungstic compound catalyzed deep desulfurization of diesel in ionic liquids was studied. It was found that tungstic com- pounds such as Na2WO4·2H2O and H2WO4, H3PW12O40, (NH4)3PW12O40·3H2O as catalysts give high sulfur removal in [Bmim]BF4 extraction and catalytic oxidative desulfurization system. However, the catalysts of WO3, H4SiW12O40 and Na4SiW12O40 exhibit lower sulfur removal. Both simple tungstic and molybdic compounds lead to low removal of sulfur in water-immiscible ionic liquids.In order to improve the removal of simple molybdic compounds in water-immiscible ionic liquids, four molybdenum peroxo amino acid complexes are synthesized, such as MoO(O2)2C2H5NO2, MoO(O2)2·-C3H7NO2H2O, MoO(O2)2·C4H7NO4H2O and MoO(O2)2C5H9NO4·H2O. Four catalysts are characterized by EA, gravimetry, chemistry titration, TG-DSC, FT-IR and DRS to determine the composition and structure. It was found that molybdenum peroxo amino acid complexes as catalysts give high sulfur removal in both [Bmim]BF4 and [Bmim]PF6 ECODS system. The mechanism and difference of simple molybdic compound and molybdenum peroxo amino acid complex as catalys in process of ECODS was deeply studied and clarified by UV-Vis and IR.Four tungsten peroxo amino acid complexes are synthesized, such as WO(O2)2·C2H5NO2H2O, WO(O2)2·2C3H7NO2H2O, WO(O2)2·2C4H7NO4 and WO(O2)2·3C5H9NO4. Four catalysts are characterized by EA, gravimetry, chemistry titration, TG-DSC, FT-IR and DRS to determine the composition and structure. Reaction time, temperature, amout of oxidizing agent and ionic liquid were optimized. It was found that tungten peroxo amino acid complexes as catalysts give high sulfur removal in both [Bmim]BF4 and [Bmim]PF6 ECODS system. In the case of the system containing simulated diesel (DBT), H2O2, WO(O2)2·2C3H7NO2·H2O and [Bmim]PF6, extraction and catalytic oxidation increased the sulfur removal to 98.9%.This dissertation develops a novel method of ionic liquid extraction coupled with catalytic and oxidative desulfurization. The research provides a new scientific basis for tungsten and molybdenum complex-catalyzed oxidation deep desulfurization of simulated diesel in ionic liquids. It is important to fundamental research and practical applications.
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