چكيده به لاتين
In recent years, strict laws for sulfur content of hydrocarbon fuel have been assigned over the world. Therefore, in according to limitation of traditional hydrodesulfurization in removal dibenzothiophene compounds, oxidative desulfurization has been considered as a promise replacement in recent years. In this regard, for the first time, synthesis and study of new type of emulsion catalysts with ionic liquid based solvents has been proposed for the extractive-catalytic-oxidative desulfurization. In this study, at first, the emulsion catalysts, Q6+xP2W18-xVxO62 with different amount of vanadium (x= 0, 1, 3, 5) and various type of ammonium cation included CTA and TBA were synthesized. All catalysts were characterized by elemental analysis, FT-IR, IR, XRD, SEM, Uv-vis DRS, XPS, 31P MAS NMR and TGA. The morphological study of catalysts showed that the catalyst, [CTA]11P2W13V5O62, has a high electron donor and high oxidative power in comparison with other catalysts. In order to screen of the best catalyst, the catalytic oxidative desulfurization was done under the minimal conditions. The results showed that the hybrid catalysts with CTA cation and the maximum amount of vanadium ([CTA]11P2W13V5O62) had the best yield. The optimum amount of catalyst was determined 7.5 g/L by using Taguchi experimental method and the minimum amount of oxidizer and without any extractive solvents. The Basionic solvent ([Bmim]mSO4) and DES solvents have been used accompanying to oxidative process to improve the yield of desulfurization. The results demonstrated that it could be desulfurized up to 90 % and denitrogenized 100 % from the model oil containing 500 ppmw sulfur (various type of sulfur compounds like dibenzothiophene, benzothiophene and 4,6-dimethyl dibenzothiophene) and 445 ppmw quinoline solved in iso-octane contacting 20 v-% toluene after 45 minutes by using [Bmim]mSO4 solvent with volume ratio to model oil, 1 to 6, oxidizer to oxidized compounds volume ratio, 6 and under 70 oC and atmospheric pressure. Under mentioned optimum conditions and higher sulfur content, 1500 ppmw, the ability of the best catalyst was studied and the results revealed that the 70 % desulfurization in one-step was achieved. In order to improve the yield, the two-oxidative-extractive-step desulfurization was also studied. The results showed that the yield of desulfurization was improved up to 87 % for model fuel containing 1500 ppmw sulfur and 1335 ppmw quinoline. In final step, the behavior of proposed desulfurization system was studied for real diesel oil containing 1235 ppmw sulfur. The results demonstrated that the sulfur content of real diesel oil could be reduced to 7 ppmw by using two steps. Finally, the recirculation and reusability of emulsion catalyst and solvent was studied. The result showed that the mixture could be 4 times from real diesel oil, at least 10 times from 500 ppmw model oil and 4 times from 1500 ppmw model oil.
