Extractive Desulfurization of Fuel Oils with Thiazolium-Based Ionic Liquids

Abstract

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of fuel oils because of the limitation of the traditional hydrodesulfurization method in catalytically removing thiophenic sulfur compounds. In this work, four thiazolium-based ILs, that is, 3-butyl-4-methylthiazolium dicyanamide ([BMTH][DCA]), 3-butyl-4-methylthiazolium thiocyanate ([BMTH][SCN]), 3-butyl-4-methylthiazolium hexafluorophosphate ([BMTH][PF 6 ]), and 3-butyl-4-methylthiazolium tetrafluoroborate ([BMTH][BF 4 ]), are synthesized. The extractive capability of these ILs in removing thiophene (TS) and dibenzothiophene (DBT) from model fuel oils is investigated. [BMTH][DCA] and [BMTH][SCN] present better extractive desulfurization capability than [BMTH][BF 4 ] and [BMTH][PF 6 ], which may be ascribed to the additional pÀp interaction between -CN (in [BMTH][DCA] and [BMTH][SCN]) and thiophenic ring (in TS and DBT); DBT in diesel fuel is more efficiently extracted than TS in gasoline. [BMTH][DCA] offers the best desulfurization results, where 64% and 45% sulfur removal are obtained for DBT and TS, respectively, at IL:oil mass ratio of 1:1, 25 C, 20 min. [BMTH] [DCA] is thus selected to systematically investigate the effects of temperature, IL:oil mass ratio, initial sulfur content, multiple-extraction, and IL regeneration on desulfurization. The mutual solubility of [BMTH][DCA] with fuel oil is also determined. It is observed that the desulfurization capability is not too sensitive to temperature and initial sulfur content, which is desired in industrial application; the sulfur contents in gasoline and diesel fuel are reduced from 558 ppm to 20 ppm (after 5 cycles) and from 547 ppm to 8 ppm (after 4 cycles), respectively. This work may show a new option for deep desulfurization of fuel oils.

Synthesis, characterization, and application of 1-butyl-3-methylimidazolium thiocyanate for extractive desulfurization of liquid fuel

“…Then, the product was washed thrice with ethyl acetate. The remaining ethyl acetate was removed by heating at 60°C under vacuum for 2 h. The solution was filtered and the remaining resulting product was obtained [BMIM]Cl (Chen et al 2012;Mochizuki and Sugawara 2008).…”

“…The synthesis and characterization by NMR of 1-butyl-3-methylimidazolium thiocyanate [BMIM]SCN was reported. This imidazolium-based IL has been used in extraction of cobalt from nickel salts, and in liquid membrane (Chen et al 2012).…”

FeCl3 Based Imidazolium Ionic Liquids as Novel Solvents for Extractive–Oxidative Desulfurization of Liquid Fuels

“…However, few studies are found in the literature that spotlight on the desulfurization related equilibria while including other compounds such as aromatic hydrocarbons or nitrogen containing compounds. The chemistry of imidazolium cations is known and some imidazolium salts are commercially available [27].…”

Correlation of the Solubilizing Abilities of 1-Butyl-1-methyl-pyrrolidinium Tris(pentafluoroethyl)trifluorophosphate, 1-Butyl-1-methylpyrrolidinium Triflate and 1-Methoxyethyl-1-methylmorpholinium Tris(pentafluoroethyl)trifluorophosphate

“…The solvation parameter model is based on two liner free energy relationships (LFERs), the first relationship describes solute transfer between two condensed phases: log 10 P = c p + e p ·E + s p ·S + a p ·A + b p ·B + v p ·V (1) and the second relationship involves solute transfer from the gas phase to a condensed phase log 10 K = c k + e k ·E + s k ·S + a k ·A + b k ·B + l k ·L (2) where P and K refer to the solute's condensed phase-to-condensed phase partition coefficient (often water-to-organic solvent partition coefficient) and gas-to-condensed phase partition coefficient, respectively. For ionic liquid solvents, Sprunger et al [27,[34][35][36] …”

“…Ravilla and Banerjee [1] recently investigated 1-ethyl-3-methylimidazolium methylsulfonate, 1-ethyl-3-methylimida-zolium ethylsulfate and 1-ethyl-3-methylimidazolium acetate as green solvents for the denitrification of diesel oil at T = 298.15 K and atmospheric pressure. Chen and coworkers [2] synthesized four thiazolium-based ILs (i.e., 3-butyl-4-methylthiazolium dicyanamide, 3-butyl-4-methylthiazolium thiocyanate, 3-butyl-4-methylthiazolium hexafluorophosphate and 3-butyl-4-methylthiazolium tetrafluoroborate) for use in extractive desulfurization of fuel oils. The authors reported that a 64 % dibenzothiophene and 45 % thiophene removal could be achieved using 3-butyl-4-methylthiazolium dicyanamide.…”