Glycerol acetylation with acetic acid over Purolite CT-275. Product yields and process kinetics

An important category of glycerol derivatives, having multiple practical applications, are its esters with acetic acid (acetates or acetins). The most common preparation method of glycerol acetates is the direct esterification of glycerol with acetic acid in presence of acid catalysts. In this work is investigated the liquid phase glycerol esterification with acetic acid, catalyzed by the commercial Purolite CT-275 ion exchange resin. In this aim, there were performed batch experiments, in a stirred autoclave reactor, at initial acetic acid to glycerol molar ratios between 4 and 9 and temperatures between 70 and 110 °C. The experimental data were used to develop a kinetic model, based on the Langmuir Hinshelwood theory. The components activities, involved in the calculation of the reaction rates, were evaluated by the UNIFAC Dortmund method. The proposed kinetic model predicts with good accuracy the products distribution dependencies on the reactants molar ratio and reaction temperature. The calculated values of the Weisz-Prater criteria evidenced influences of the internal diffusion on the esterification process kinetics, over an initial reaction time interval. The proposed kinetic model is directly utilizable in the commercial process analysis and design calculations.