Correlation and prediction of excess quantities and vapor - Liquid equilibria of alkyl esters + terf-butyl alcohol: Experimental data for propyl esters + tert-butyl alcohol

Abstract

In this work, the experimental values for excess quantities H mE and V mE are presented at two temperatures and the isobaric vapor - liquid equilibrium data (VLB) at 101.32 kPa for binary systems comprised of the first four propyl alkanoates with tert-butyl alcohol. It was demonstrated for the four mixtures that (∂H mE/∂T)p,x < 0 and (∂V mE/∂T)p,x > 0. Experimental data of VLE were checked with the Fredenslund method, which showed the systems to be thermodnamically consistent. Only the binary mixture (propyl methanoate + tert-butyl alcohol) presented an azeotropic point at ester concentration of 0.621 and at a temperature of 350.52 K. Simultaneous correlations are performed with the VLE data and the excess enthalpies with different known thermodynamic mathematical models (Wilson, NRTL, and UNIQUAC) with temperature-dependent coefficients and another polynomial model proposed by our research group. The latter gave the most acceptable correlation for the mixtures studied. The original UNIFAC model, with the interaction parameters of Hansen et al. (Ind. Eng. Chem. Res. 1991, 30, 2355-2358), did not give good VLE predictions, while the version of Gmehling et al. (Ind. Eng. Chem. Res. 1993, 52, 178-193) produced acceptable estimations of VLE data, except for methanoates. Estimations of excess enthalpies with this model always produced lower values with an average error of 20 %. In this work, the results obtained for the 16 mixtures (alkyl esters + tert-butyl alcohol) are evaluated. © 2006 American Chemical Society.