Separation of pyridine from heptane with tricyanomethanide-based ionic liquids

• The experimental LLE in ternary systems.
• High solubility of pyridine in [BMIM][TCM], [BMMOR][TCM], and [BMPY][TCM].
• Extraction of nitrogen-compounds from alkanes.
• [BMMOR][TCM] may be proposed as entrainer for the denitrogenation of fuel oil.

Recent approaches employ three tricyanomethanide-based ionic liquids (ILs) as selective solvents of the extraction of pyridine as a model compound of nitrogen compounds in fuels from heptane at T = 298.15 K and ambient pressure. Experimental data for liquid–liquid phase equilibrium (LLE) were obtained for three ternary systems. The 1-butyl-3-methylimidazolium tricyanomethanide, [BMIM][TCM], 1-butyl-1-methylmorpholinium tricyanomethanide, [BMMOR][TCM] and 1-butyl-1-methylpyridinium tricyanomethanide, [BMPY][TCM] were used due to their immiscibility with gasoline and diesel, negligible vapor pressure, and high selectivity to sulfur- and nitrogen-containing compounds. All of proposed ILs showed similar excellent selectivity with the best Smax = 609.3 for and similar high distribution ratio with βmax = 9.2 for [BMMOR][TCM] in the extraction of pyridine from heptane and much higher to what is currently published for different ILs. Chromatography analysis showed that IL was not present in the heptane layer. This eliminate the process of the separation of the solvent from the raffinate layer. The data obtained have been correlated with the non-random two liquid NRTL model. The experimental tie-lines and the phase composition in mole fraction in the ternary systems were calculated with an average root mean square deviation (RMSD) of 0.004.

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