Separation of aliphatic from aromatic hydrocarbons and sulphur compounds from fuel based on measurements of activity coefficients at infinite dilution for organic solutes and water in the ionic liquid N,N-diethyl-N-methyl-N-(2-methoxy-ethyl)ammonium bis(trifluoromethylsulfonyl)imide

Abstract

The activity coefficients at infinite dilution, γ13∞, for 53 different solutes including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, ethers, ketones, thiophene, acetonitrile, pyridine, 1-nitropropane and water in the ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide, [COC2N1,2,2][NTf2] were determined using inverse gas-liquid chromatography. The experiment has been performed at five temperatures over the range of (318.15 to 358.15)K. From experimental results, the partial molar excess Gibbs energy, ΔG1E,∞, enthalpy ΔH1E,∞ and entropy term TrefΔS1E,∞ at infinite dilution were calculated. Additionally, the gas-liquid partition coefficients of the solutes, KL were calculated. The value of selectivity, S12∞ and capacity, k2∞ at infinite dilution for hexane/benzene, cyclohexane/benzene, heptane/thiophene and heptane/pyridine separation processes were calculated directly from γ13∞. These parameters are compared to literature values of S12∞ and k2∞ for other ionic liquids and NMP, or sulfolane – solvents commercially used on an industrial scale in separation processes. Moreover, physicochemical properties of pure ILs that is: density, viscosity and surface tension have been determined as a function of temperature and basic thermal properties of pure [COC2N1,2,2][NTf2] were measured using DSC technique.