Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

To design and optimize the noncatalytic supercritical process for biodiesel production based on ethanolysis and using carbon dioxide as a cosolvent, thermodynamic models are required to predict the fluid phase equilibria of the various mixtures involved within. This work is an attempt to extend the PPR78 predictive cubic equation of state to CO2 + ethyl ester systems. To do so, 105 mixture critical points of 11 CO2 + (saturated and unsaturated) ethyl ester mixtures were preliminary measured using a synthetic-dynamic apparatus. With the use of these data as well as vapor liquid equilibrium data collected in the open literature, 2 new groups were added to the PPR78 model (the ester group -COO and the ethyl acetate group) and 10 PPR78 group-interaction parameter values were determined. Although the PPR78 model offers a good predictive capacity, it is observed that the prediction may deteriorate with the ethyl ester chain length or the presence of double C-C bonds.