Vapor-liquid equilibria at 101.32 kPa and excess properties of binary mixtures of butyl esters + tert-butyl alcohol

Abstract

This work shows the experimental values of excess properties H Em and VmE at two temperatures and the isobaric vapor-liquid equilibria at 101.32 kPa for binary systems composed of the first four butyl alkanoates with tert-butyl alcohol. None of the mixtures presented azeotropes, and all of the experimental data p-T-x-y were checked with a point-to-point test, proving to be thermodynamically consistent. The correlation of vapor-liquid equilibria and excess enthalpies was done simultaneously using different expressions with temperature-dependent coefficients. The model that gave the most acceptable correlation for the four mixtures was the polynomial expression proposed in this work. The NRTL model gave acceptable estimations of HmE, and the UNIQUAC, of equilibrium data. Two versions of the UNIFAC model were used: the original one with parameters by Hansen et al. and the version modified by Gmehling et al., which predicts the equilibrium data as the mixing enthalpies. This last version estimated HmE with differences of around 20% for the four mixtures at different temperatures. The predictions made for equilibria are considered to be acceptable for the mixtures (butyl propanoate or butanoate + tert-butanol). The estimations made using the original version by Hansen et al. were not good. © 2005 American Chemical Society.