Azeotrope breaking for the system ethyl tert-butyl ether (ETBE) + ethanol at 313.15 K and excess properties at 298.15 K for mixtures of ETBE and ethanol with phosphonium-based ionic liquids

Isothermal vapor–liquid equilibria for the ternary system {ethyl tert-butyl ether (ETBE) + ethanol + trihexyltetradecylphosphonium chloride ([P666,14][Cl]) or trihexyltetradecylphosphonium bis(2,2,4-trimethylpentyl)phosphinate ([P666,14][TMPP])} have been determined at 313.15 K using headspace gas chromatography (HSGC). The addition of a small amount of ionic liquids (ILs) to the system ETBE + ethanol produced an important salting-out effect. The azeotrope disappeared by varying the mole fraction of ILs from 0.05 to 0.10. The experimental VLE data were correlated using the Wilson equation. In addition, excess molar volumes (VE) and deviations in molar refractivity ((R) data at 298.15 K are reported for the binary systems {ETBE + [P666,14][Cl]}, {ETBE + [P666,14][TMPP]} and {ethanol + [P666,14][TMPP]} by a digital vibrating tube densimeter and a precision digital refractometer. The VE and (R were well correlated according to the Redlich–Kister equation.

► Ethyl tert-butyl ether (ETBE) is considered as a benign gasoline. ► VLE data for the systems {ETBE + ethanol + [P666,14][Cl] or [P666,14][TMPP]}. ► VE and (R for the binary systems {ETBE + [P666,14][Cl] or [P666,14][TMPP]}. ► VE and ΔR showed a negative deviation. ► Ternary VE and ΔR were calculated from the binary data.