Phase equilibrium measurements and thermodynamic modeling of {CO2 + diethyl succinate + cosolvent} systems

This work reports experimental phase equilibrium data for the binary systems {CO₂(1) + diethyl succinate(2)} and {CO₂(1) + ethyl acetate(2)}, and for the ternary systems {CO₂(1) + diethyl succinate(2) + ethanol(3)} and {CO₂(1) + diethyl succinate(2) + ethyl acetate(3)}. The experiments for the binary system {CO₂(1) + diethyl succinate(2)} were carried out at temperatures ranging from 308 K to 358 K, and temperatures ranging from 303 K to 343 K for {CO₂(1) + ethyl acetate(2)} as well as for all ternary systems. Only vapor-liquid equilibria were observed for all systems. The experimental measurements were carried out in a high-pressure variable-volume view cell containing a movable piston, which allows pressure control inside the cell. Binary and ternary systems were modeled with the Peng-Robinson cubic equation of state with the van der Waals quadratic mixing rule (vdW2). The presence of a cosolvent (ethanol and ethyl acetate) decreased the saturation pressures of either bubble or dew points compared to the binary system CO₂ + diethyl succinate, increasing the solubility of diethyl succinate in CO₂.