High-Pressure Phase Equilibria in Ternary Systems of Propionic Acid and Water with Ethane, SF₆, or Refrigerant 13 (CCIF₃), 23 (CF₃H), or 116 (C₂F₆)

Vapor-liquid and liquid-liquid equilibrium compositions are presented for the ternary systems of H₂O and propionic acid with refrigerant 23 (R23; CF₃H), ethane, R13 (CCIF₃), SF₆, and R116 (C₂F₆) at 313 K, near the critical temperature of each solvent. Equilibria for most systems were determined at 15.0 MPa; the subcritical solvent SF₆ was studied at a pressure just above its vapor pressure at 313 K (4.0 MPa). The distribution coefficient of propionic acid between the solvent phase and the aqueous phase increases with the water solubility of the solvent. Only the fully fluorinated solvents SF₆ and R116 (C₂F₆) are immiscible with proplonic acid under the conditions of interest. Where solvent + water binary data are available, the experimental data for the ternary systems were correlated by using a cubic equation of state and a density-dependent mixing rule with model parameters derived from binary data only.