Isobaric vapor-liquid equilibria and excess properties for the binary systems of methyl esters + heptane

Abstract

The behavior was investigated for several binary mixtures that were composed of five methyl esters (from methanoate to pentanoate) with n-heptane, by using different thermodynamic quantities as obtained from experimental results such as isobaric vapor-liquid equilibria at the pressure 101.32 kPa and the corresponding excess properties. The equilibrium data show that all the mixtures reveal a positive deviation from ideality and that they are consistent with a point-to-point test. All the mixtures studied, with the exception of methyl pentanoate + n-heptane, reveal an azeotrope. Various equations were used to treat the equilibrium data. The use of a new polynomial correlation with temperature-dependent coefficients was deemed to be convenient. Various theoretical models were used in this study, including UNIFAC and ASOG, but the Gmehling et al. version was found to be more acceptable when estimating excess enthalpies with differences of between (3 and 17)%.