Triethylene Glycol as Entrainer for 1-Propanol + Water Mixtures: Vapor-Liquid Equilibria, Excess Enthalpies, and Excess Gibbs Energy Model Parameters

For the separation of the azeotropic mixture 1-propanol + water, triethylene glycol as a possible entrainer is investigated. For this purpose, experimental data for isobaric vapor-liquid equilibria of 1-propanol + triethylene glycol and water + triethylene glycol at 10 kPa, as well as 1-propanol + water at 101.32 kPa, is determined, along with excess enthalpy data of 1-propanol + triethylene glycol at 298.15, 313.15, and 328.15 K. The binary subsystems' vapor-liquid equilibria, excess enthalpies, and activity coefficients at infinite dilution are used for regression and assessment of excess Gibbs energy model parameters, including the Wilson and NRTL approaches. For one particular NRTL model parameter set, high agreement with measured ternary vapor-liquid equilibrium data at 101.32 kPa is achieved. The general feasibility of an extractive distillation using triethylene glycol as an entrainer is evaluated, resulting in a minimum molar triethylene glycol entrainer fraction of 0.35.