Desulfurization of ternary mixtures of n-paraffins (C12 or C16) + thiophene + two methylimidazolium dicyanamide (DCA)-based ionic liquids

Abstract

Reducing sulfur levels in fuels has gained significant importance in the oil refining sector to curb harmful emissions of sulfur oxides (SO_x), impacting public health and the environment. We conducted liquid-liquid extractions of thiophene from n-paraffin compounds, employing 1-ethyl-3-methylimidazolium dicyanamide [emim][DCA] and 1‑butyl‑3-methylimidazolium dicyanamide [bmim][DCA] ionic liquids at 313.15 K and atmospheric pressure (101.3 kPa). The study involved determining liquid-liquid equilibrium data for three ternary systems: {n-dodecane (1) + thiophene (2) + [bmim][DCA] (3)} and {n-hexadecane (1) + thiophene (2) + [emim][DCA] or [bmim][DCA] (3)}. Furthermore, we computed and compared distribution ratios and selectivity values across these systems to assess their desulfurization competency. The thermodynamic nonrandom two-liquid (NRTL) model was employed to correlate the experimental data. UNISIM steady-state simulator was used to estimate the extraction efficiency of thiophene from n-C₁₆ as a model diesel fuel.