Knowledge of phase equilibria and critical properties of CO2 + carboxylic acid systems is essential for supercritical fluid extraction (SCFE) processes, such as oil deacidification. However, modeling these systems is challenging due to their highly asymmetrical behavior. In this study, we apply the Group Contribution with Association Equation of State (GCA-EOS) to model vapor−liquid and liquid−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 set of parameters, we validate the model against experimental data for C2−C20 acids, temperatures from 293 K to 473 K, and pressures up to 400 bar. The model successfully predicts phase equilibria across the entire homologous series, making it a reliable tool for assessing the multiphase behavior of these systems in SCFE applications.

中文翻译：

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使用 GCA-EOS 进行多相平衡建模。第 III 部分：CO2 与同源系列羧酸


了解 CO2 + 羧酸系统的相平衡和关键特性对于超临界流体萃取 （SCFE） 工艺（如油脱酸）至关重要。然而，由于这些系统的行为高度不对称，因此对这些系统进行建模具有挑战性。在这项研究中，我们应用具有关联状态方程的群贡献 （GCA-EOS） 来模拟 CO2 + 羧酸同源系列的气-液和液-液平衡。GCA-EOS 之前已针对烷烃和醇类进行了验证，现已扩展到涵盖短链和长链羧酸。使用一组参数，我们根据 C2-C20 酸、293 K 至 473 K 的温度和高达 400 bar 的压力的实验数据验证模型。该模型成功地预测了整个同源序列的相平衡，使其成为评估 SCFE 应用中这些系统的多相行为的可靠工具。