Study On Selective Oxidation Dsulfurization Of FCC Gasoline In Liquid Phase

A considerable attention had been focused on automobile-exhaust pollution due to the increasingly content of sulfur in crude oil and the recognition of environmental consciousness. Strict regulations limiting the sulfur content had been introduced in some countries. Conventional hydrodesulfurizaiton technology if used for this process needed severe operating conditions, such as high hydrogen pressure and reaction temperature, which were unfavorable for commercial purpose. Much interest, therefore, had been focused on oxidative desulfurization technology, which could be operated on moderate conditions and reaction could be processed without consuming hydrogen. In addition, it had following advantages: (1) the nitrogen compounds and substituted thiophenes could be removed; (2) the side-product was organic sulfide, which may be used as industrial material; (3) it was an environment protection technique due to the decreasing emission of carbon dioxide.In this text, the oxidative desulfurization of thiophene as a model compound was studied over the system combined by the catalyst of heteropoly acids, the oxidant H2O2 and quaternary ammonium salt phase-transfer catalyst. The influence of cation of quaternary ammonium salt phase-transfer catalyst and the structure on the oxidative-desulfurization rate was investigated. It was shown that the desulfurization rate was up to 93.1%. The oxidation mechanism of thiophene and the final product of oxidative desulfurization were discussed.The processing conditions of oxidative desulfurization of thiophene were studied over the system combined by catalyst of heteropoly acids- quaternary ammonium salt, and the oxidant H2O2. The results showed that the catalyst was active because it could decrease the interfacial resistance and facilitate the oxidative desulfurization. The processing conditions of oxidative desulfurization of thiophene were investigated over the system combined by catalyst of zinc ferrite supporting on phosphotungstic acid, and the oxidant H2O2. It was shown that the active centre of catalyst was increased and distributed equably by increasing the specifics surface area of catalyst.According to the above analysis, the oxidative desulfurization of FCC was studied over the system combined by the catalyst of heteropoly acids, the oxidant H2O2 and quaternary ammonium salt phase-transfer catalyst. It was shown that the desulfurization rate was up to 83.6%. Quaternary ammonium salt phase-transfer catalyst could decrease the resistance of water-oil interface; its cation could combine with over-oxygen-heteropoly anion, and avoid the solvent effect, thus the activity of heteropoly acids catalysts increased. The oxidation desulfurization mechanism of FCC and the final product were determined.