The Ethylbenzene/Styrene Preferential Separation with Ionic Liquids in Liquid–Liquid Extraction

摘要

The objective of this work was to explore the feasibility of using ionic liquids (ILs), namely N -ethyl- N -methylmorpholinium dicyanamide, [EMMor][DCA], (3-hydroxypropyl)-1-methylmorpholinium dicyanamide, [ N -C~(3)OHMMor][DCA], 1-(3-hydroxypropyl)-3-methylimidazolium dicyanamide, [ N -C~(3)OHMIM][DCA], 1-(3-hydroxypropyl)pyridinium dicyanamide, [ N -C~(3)OHPy][DCA], (3-cyanopropyl)pyridinium dicyanamide, [ N -C~(3)CNPy][DCA], and (3-cyanopropyl)methylpyrrolidinium dicyanamide, [ N -C~(3)CNMPyr][DCA] for the separation of ethylbenzene and styrene. The liquid–liquid equilibrium (LLE) data in ternary systems of {IL (1)?+?styrene (2)?+?ethylbenzene (3)} at T ?=?298.15?K and ambient pressure is presented for the six ILs synthesized by us. The final chromatography analysis of the composition of tie-lines has shown that the studied ILs are not found in the raffinate phase and they show interesting results on the selectivity and solute distribution ratio for styrene extraction. A comparison of different ILs is presented for the studied separation problem. It was observed that the best separation selectivities were found for [ N -C~(3)CNPy][DCA] ( S ~(Av)?=?2.38) and [ N -C~(3)OHMMor][DCA] ( S ~(Av)?=?2.42) in comparison with other studied ILs in this work and those presented in the literature. While the data presented here are useful from a theoretical standpoint, the possibility of applications for these ILs in technological processes is questionable because of low solute distribution ratios, especially those calculated from the masses [ N -C~(3)CNPy][DCA] ( β ~(MAv)?=?0.08) and [ N -C~(3)OHMMor][DCA] ( β ~(MAv)?=?0.07). The experimental tie-lines were correlated with the non-random two liquid NRTL model.