Study On Application Of Ionic Liquids In Desulfurization Of Fuel Oil

Along with more attention being paid to environment protection worldwide, most countries have made laws or regulations to restrict the sulfur content in fuel oil with a more rigorous standard. Among these techniques, the extraction desulfurization with ionic liquids, which has many advantages such as low investment, simple techniques, mild conditions, easy separation etc, shows promising as an approach for the deep desulfurization of fuel oil.Several lower cost ionic liquid, such as [Et3HN]Cl/CuCl and [HMim]Cl/CuCl, were prepared and characterized. The effect of experiment condition to desulfurizaiton rate was researched. The sulfur removal were 86.1% and 86.8% respectively when [HMim]Cl/CuCl and [Et3HN]Cl/CuCl ionic liquid were used for extraction desulfurization.In previous researches, ionic liquids employed to desulfurize from fuels are mostly N-alkylimidazolim-based ionic liquids. In this thesis, N-alkyl-pyridinium-based ionic liquids were used in extractive desulfurization. The properties of N-alkyl-pyridinium-based ionic liquids were studied for the first time. The desulfurization ability of ionic liquids connects with the chemical property of ionic liquids, such as the cation or anion structure, size of ionic liquids. With the same anion, increase of cation size by the substitution of a longer alkyl group to the pyridium ring was responsible for the increase of the extractive capacity for thiophene. But a similar phenomenon did not hold with increasing anion size when the cations of ionic liquids were same; desulfurization ability of ILs connects with the chemical property of anion. We also researched the extraction-oxidation desulfurization with N-alkyl-pyridinium-based ionic liquids.Extraction/Oxidation with ionic liquids and O3 are combined to desulfurize the sulfur compound in FCC gasoline. The desulfurization rate could reach 87.5%. O3 oxidation process could be promoted by the addiation of OH-.Br?nsted ionic liquid [Hnmp]BF4 was used to be a catalyst and extractant for desulfurization of model oil and actual diesel fuel. In this process, DBT was oxidized in the ionic liquid phase as it was extracted from oil phase, so a continuous decrease in the concentration of DBT in n-octane was observed for each solvent during the oxidation process. [Hnmp]BF4 is not only the extractant but also the catalyst. One of its catalytic roles is to decompose hydrogen peroxide to form hydroxyl radicals. DBT in the ionic liquids phase was oxidized to its corresponding sulfone by the hydroxyl radicals. Sulfone did not exist in the oil phase because of the high polarity of ionic liquid. DBT sulfone can be detected in the ionic liquid phase.In addition, the ionic liquid was also effective on the ODS of actual diesel fuel. 99.4% sulfur-containing compounds which present in the actual diesel fuel can be removed. The results show that ionic liquids [Hnmp]BF4 could be used in deep desulfurization.