Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

This work shows the experimental data of excess properties at several temperatures and the vapor.liquid equilibria (VLE) obtained for four binary systems of alkyl methanoates (methyl to butyl) with decane, all measured at constant pressure of 101.32 kPa. The isobaric VLE data were thermodynamically consistent according to the Fredenslund test and did not present an azeotrope. The experimental data of HEm and VEm showed that the mixing process of the systems studied are clearly endothermic with expansion effects, and this was the case for all the mixtures in which ( delHEm / delT)p greater than 0 and ( delVEm / delT)p greater than 0. The mixing properties data indicate high interactional effects that also produce high values of gamma, especially in the system containing methyl methanoate, caused by associative problems that diminish with increased alkanolic chain length of ester. Mixing quantities were correlated with a parametric model with temperature-dependent coefficients. The VLE data and enthalpies were simultaneously correlated with a general model established for excess Gibbs function, yielding an acceptable correlation in all cases. Isobaric VLE quantities were estimated with two known versions of the UNIFAC model, with very similar results. Using the parameters published in the literature for the HCOO/CH2 interaction, the UNIFAC model does not reproduce well the data that characterize VLE for the mixtures studied, although the version of Gmehling et al. [8] using the same set of parameters, makes an acceptable qualitative and quantitative prediction of HEm .