An optimized potential for phase equilibria calculation for ketone and aldehyde molecular fluids

Abstract

An extension of the Anisotropic United Atoms intermolecular potential model is proposed for ketone and aldehyde molecular fluids. The electrostatic part of the intermolecular potential is represented by a distribution of atomic charges obtained from fitting to an ab initio electrostatic potential. The repulsion–dispersion interaction parameters for methyl and methylene groups are taken from a previous study on alkane fluids. Effective non-bonded (Lennard-Jones) parameters are then derived for the carbon and oxygen atoms of the ketone group from fitting to a set of experimental data. The Lennard-Jones parameters for the hydrogen atom of the aldehyde group are then obtained from fitting to selected experimental data without readjusting the carbon, oxygen, methyl or methylene parameters. The resulting potential is tested on liquid properties at atmospheric pressure and vapour–liquid phase equilibria of several ketone and aldehyde fluids. The agreement between simulated results obtained through Gibbs Ensemble Monte Carlo simulations and experimental data is very good.