Preparation Of Double Cation Liquid And Its Use In Desulfurization Of Vehicle Fuel

It is of great significance to accelerate the upgrading of refined oil quality,which can improve the environment,governance haze pollution and promote sustainable green development.So reducing the content of harmful substances in vehicle fuel,especially sulfur content,is very important to reduce the emission of vehicle pollutants.Therefore,the research and production of low-sulfur or even non-sulfur clean vehicle fuel has has become the concern of the refinery and researchers.Ionic liquids(ILs)have been widely used in desulfurization of vehicle fuel due to their advantages such as high stability and adjustable structure.However,the current development of ILs has some shortcomings,such as low extraction desulfurization rate and poor selectivity.Therefore,the design and synthesis of novel and efficient ILs has become the focus of research in this field.In this paper,a series of dicationic ionic liquids(DILs)were synthesized by adjusting the type and structure of anions and cations of ILs,and applied to extractive desulfurization of vehicle fuel.In this paper,two kinds of dicationic ionic liquid(DILs)with desulfurization effect were synthesized successfully.The first kind is imidazole,which is[C2(Mim)2](HSO4)2?[C4(Mim)2](HSO4)2?[C2(Mim)2](PTSA)2?[C4(Mim)2](PTSA)2;The second kind is pyridine,which is[C4(BPy)2](HSO4)2?[C2(BPy)2](PTSA)2?[C4(BPy)2](PTSA)2.Firstly,the basic physical properties of the DILs were determined.The density,viscosity,interfacial tension and acid strength ranged from 1.27 to 1.41 g/cm3,210 to 1339 mPa s,4.64-6.86 mN/m and 1.28 to 1.52,respectively.Then the structure of the synthesized DILs was characterized by FT-IR and 1H NMR spectra,which confirmed that the structure of the synthesized material was consistent with the ideal structure of the DILs.The EDS process of FCC gasoline was studied by using the synthesized DILs as extractant.The screening experiment of DILs shows that the[C2(Mim)2](HSO4)2 had the best desulfurization effect.For DIL3-DIL8,the desulfurization rate decreases with the increase of H0,while the desulfurization rate increases with the decrease of H0,that is,the desulfurization rate is positively correlated with the increase or decrease of acid strength.The experimental conditions of extraction desulfurization were investigated and optimized.Under the optimal extraction condition(extraction temperature=30?,extraction time=30 min,mass ratio of extractant to gasoline=2:1),the desulfurization ratio can reach 79.72%.After six cycles of use,the desulfurization effect is still existed.And after five-stage extraction,the sulfur content decreased from 756.4 ?g/g to 9.5 ?g/g,deep desulfurization was realized.In addition,the[C2(Mim)2](HSO4)2 was regenerated by solvent method,the structure of[C2(Mim)2](HSO4)2 before and after regeneration was compared by FT-IR and 1H NMR.It was found that the chemical structure of regenerated[C2(Mim)2](HSO4)2 did not change,and the desulfurization rate of regenerated solvents for 1#FCC gasoline still reached 76.14%,the desulfurization performance did not decrease significantly.Moreover,the suitability of[C2(Mim)2](HSO4)2 extractive desulfurization was studied for different oil products from different areas.The experimental results show that[C2(Mim)2](HSO4)2 had good adaptability to different oil for extraction desulfurization.Furthermore,the extraction desulfurization efficiency of the DILs was compared with that of the monocations ILs(MILS),and the extraction desulfurization mechanism of DILs was discussed.The experimental results show that the extraction desulfurization effect of the DILs is better than that of the MILs with the same kinds of anions and cations.According to 1H NMR characterization,it is concluded that the main way to achieve desulfurization is to extract sulfur compounds into DILs phase by the interaction of of ?-? bonds.In addition,it is inferred from the chemical shift that the DILs have larger volume cations,which is conducive to increasing the aromatic ?-electron density,producing stronger ?-? interaction between the cations and aromatic sulfides,and thus has better extraction desulfurization effect than that of MILs.