Modeling of Simultaneous Chemical and Phase Equilibria in Esterification of Acetic Acid with Ethanol in High-Pressure Carbon Dioxide

Abstract

This paper presents modeling of simultaneous chemical and phase equilibria (CPE) in esterification of acetic acid with ethanol in carbon dioxide at high pressure. Nine models based on the cubic equations of state (EOSs) have been applied. Four of them use classical mixing rules with or without the binary interaction coefficients kij, one model treats this coefficient as a function of temperature and composition, and the last four methods apply the mixing rules combining EOS and excess Gibbs free energy models. Two procedures had to be applied to obtain the agreement between the calculated and experimental results. First, the thermodynamic data referring to the acetic acid Gibbs free energies of formation were corrected to describe precisely the literature experimental chemical equilibrium constants of the considered esterification reaction in the gas phase. Second, since the literature VLE data of the system CO2−ethyl acetate turned out to be inaccurate, the binary interaction coefficients of this mixture were fitted from the ternary VLE data of the system CO2−ethanol−ethyl acetate.