Multiphase equilibria modeling with GCA-EOS. Part III: CO2 with the homologous series of carboxylic acids

Abstract

Knowledge of phaseequilibria and critical properties of CO2 + carboxylic acid systemsis essential for supercritical fluid extraction (SCFE) processes, such as oildeacidification. However, modeling these systems is challenging due to theirhighly asymmetrical behavior. In this study, we apply the Group Contributionwith Association Equation of State (GCA-EOS) to model vapor−liquid andliquid−liquid equilibria of the homologous series of CO2 +carboxylic acids. The GCA-EOS, previously validated for alkanes and alcohols,is extended to cover short and long-chain carboxylic acids. Using a single setof parameters, we validate the model against experimental data for C2−C20acids, temperatures from 293 to 473 K, and pressures up to 400 bar. The modelsuccessfully predicts phase equilibria across the entire homologous series,making it a reliable tool for assessing the multiphase behavior of thesesystems in SCFE applications.