A general mixture equation of state for double bonding carboxylic acids with >= 2 association sites

TL;DR

This paper develops a comprehensive thermodynamic model for multi-component mixtures with cyclic double bonds, allowing arbitrary association sites per molecule and incorporating hydrogen bond cooperativity, improving predictions for carboxylic acids.

Contribution

It introduces the first general multi-component solution for molecules with cyclic double bonds and arbitrary association sites, extending previous models significantly.

Findings

Accurate phase equilibrium predictions for carboxylic acids.

Hydrogen bond cooperativity significantly affects liquid phase structure.

Model outperforms previous approaches in multi-component systems.

Abstract

In this paper we obtain the first general multi-component solution to thermodynamic perturbation theory for the case that molecules can participate in cyclic double bonds. In contrast to previous authors, we do not restrict double bonding molecules to a 2-site association scheme. Each molecule in a multi-component mixture can have an arbitrary number of donor and acceptor association sites. The one restriction on the theory is that molecules can have at most one pair of double bonding sites. We also incorporate the effect of hydrogen bond cooperativity in cyclic double bonds. We then apply this new association theory to 2-site and 3 site models for carboxylic acids within the polar PC-SAFT equation of state. We demonstrate the accuracy of the approach by comparison to both pure and multi-component phase equilibria data. We also demonstrate that inclusion of hydrogen bond cooperativity has a substantial effect on liquid phase hydrogen bonding structure.