| In this study,1-ethyl-3-methylimidazolium dicyanamide IL[EMI][DCA] is synthesized by a two-step synthetic route; first, its halide salt (1-ethyl-3-methylimidazolium iodide,[EMI][I]) is synthesized by Menschutkin reaction of N-methylimidazole and iodoethane; second,[EMI][DCA] is synthesized by metathesis reaction of silver dicyanamide and the self-prepared halide salt. FT-IR and1H NMR spectroscopic analyses are employed to characterize and identify the ionic liquid.After characterization and identification, dried [EMI][DCA] with more than80%product yield is used as extractant in the desulfurization of fuel oil from real gasoline and diesel fuel and in the denitrogenation of basic and neutral N-compounds from model fuel oils. This extractant has desirable physiochemical properties, such as a molecular weight of177.21gmol-1, density of1.06gcm-3, a decomposition temperature of220℃and above all, a low viscosity of16.1cP at25℃.The desulfurization and denitrogenation analyses proceeded with the aid of a WK-2D integrated micro-coulomb analyzer and a high performance liquid chromatography (HPLC) respectively. The results are summarized. At just1min of contact with gasoline,[EMI][DCA] reduces the S-content from the initial～300ppm to262.5ppm, with a partition coefficient of0.14, and reduces the S-content in gasoline by about～17%in less than an hour of contact. On the influence of temperature, the highest S-extraction efficiency is registered at25℃in both oils; the efficiency gradually decreases with increasing temperature. Mass ratio influences the efficiency of S-extraction in such as a way that the extraction efficiency increases with rising mass ratio of IL-oil. After a6-step desulfurization, the S-content in gasoline and diesel fuel respectively lowered from199.6ppm to68.2ppm and from314.4m to121.6ppm. After five regeneration cycles, the S-extraction efficiencv_is173±3ppm for gasoline and234±4ppm for diesel fuel.In the denitrogenation study, an extraction efficiency of～70%is realized for the elimination of nitrogen compounds from the model oil containing pyridine. The N-content was reduced from～500ppm to～150ppm in a single extraction. At5,10, and20min of contact, the partition coefficient was the same, an indication that it is not sensitive to the extraction time. For the model oil containing carbazole,258.92ppm N-content was the initial N-content in the oil phase before contact with the ILextractant. After contact, the N-content in the raffinate phase was not detectable. Temperature and multiple extractions did not undergo a detailed test because at20℃, the N-content was undetected. Also, after a single extraction, the N-content was undetected. This is an indication that100%N-extraction was realized or a negligible N-content remained in the raffinate phase after contact with the ionic liquid. For the model oil containing pyridine, the extraction efficiency slightly decreases with increasing temperature; the N-Nernst partition coefficient also proves insensitive to the process, as it ranges from1.98to2.78. It can be said that that the mass ratio has some level of influence on the extraction efficiency; for example, the difference in the extraction efficiency is more than50%at2:1and1:5IL-oil. Multiple extraction is effective; after a single extraction,<70%efficiencv was obtained and after four extraetions98%was realized, while the N-Nernst partition coefficient ranges from2.29to47.88. The used [EMI][N(CN)2] was recovered and recycled with good efficiency. This work furnishes new options for the extractive uesuflurzation ana denitrogenation of fuel oils with ILs. |
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