High-pressure density and vapor–liquid equilibrium for the binary systems carbon dioxide–ethanol, carbon dioxide–acetone and carbon dioxide–dichloromethane

Abstract

An apparatus for the measurement of vapor–liquid equilibrium (VLE, P–T–x) data and density of saturated-liquid and high-pressure liquid phase of compressed gas-organic solvent systems was designed, built and tested. A synthetic method, with recirculation of the liquid phase through a high-pressure densimeter by a magnetic driven centrifugal pump, was used. The thermodynamic equilibrium was reached in a visual cell with variable volume ranging between 30 and 60 cm 3. The compositions of the phases were evaluated by external gravimetric method. The estimated accuracy of the measured data was ±0.02 K for temperature, ±0.05 MPa for pressure, ±0.005 in mole fraction for liquid compositions and ±0.05 g/L for liquid density. Vapor–liquid equilibrium data and saturated-liquid density were obtained for the following systems: carbon dioxide–ethanol and carbon dioxide–acetone at 291.15, 303.15, 313.15 and 323.15 K and carbon dioxide–dichloromethane at 291.15, 303.15 and 311.15 K. For the latter system, high-pressure liquid density data were measured up to 18 MPa. The experimental data were correlated by both Peng–Robinson and SAFT equation of state. SAFT EOS gives better correlations of vapor–liquid data and accurate predictions of high-pressure density of the liquid phase.