Modeling phase equilibria in mixtures of mono- and dicarboxylic acids with hydrocarbons.

Abstract

In this work, a group contribution equation of state that specifically takes into account association effects (GCA-EOS) is extended to model mono- and di-carboxylic acids and their mixtures with alkanes, alkenes, and cycloalkanes. Given the predominant effect of association on the behavior of these mixtures, the acid monomer fractions in the liquid and vapor phases are set as a restriction in the parameterization of the model. The parameters are correlated with a databank comprising 1800 experimental data on phase equilibria and infinite dilution activity coefficients data, which encompass a temperature and pressure range of 236-524 K and 0.001-60 bar, respectively. The new set of GCA-EOS parameters allows a good prediction of vapor-liquid, liquid-liquid, and solid-liquid equilibrium conditions, as well as infinite dilution activity coefficients of binary and ternary mixtures containing monocarboxylic acids and hydrocarbons. We also show that this parameterization allows a qualitative and, in some cases, quantitative prediction of pure dicarboxylic acids and its mixtures with other acids and hydrocarbons.