Vapor–Liquid Equilibrium Measurements of Binary and Ternary Systems of Carbon Dioxide, Dimethyl Carbonate, Acetonitrile, and Propylene Carbonate

Vapor–liquid equilibria (VLE) of three binary (CO2/dimethyl carbonate, CO2/propylene carbonate, and CO2/acetonitrile) and ternary mixtures (CO2/dimethyl carbonate/propylene carbonate, CO2/dimethyl carbonate/acetonitrile, and CO2/propylene carbonate/acetonitrile) were measured at 313, 333, and 353 K and at pressures up to approximately 200 bar using a variable-volume view cell coupled with gas chromatography (GC) analysis. These measurement results and data collected from earlier works were used to model the phase behavior of these mixtures. Two thermodynamic models were applied to represent the bubble-pressure (pbubl) and vapor-phase composition data (yi): a cubic equation-of-state/excess Gibbs free energy (CEoS/GE) model and the statistical associating fluid theory-γ Mie group-contribution (SAFT-γ Mie) equation of state. For the yi data, the Chrastil correlation was also adopted to test the performance of thermodynamic EoSs. The CEoS/GE model provided a satisfactory correlation of the pressure–composition data, while the SAFT-γ Mie model exhibited good performance in representing ternary data when unlike-interaction parameters were properly adjusted based on binary VLE data.