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

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 60cm(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. (C) 2004 Elsevier B.V. All rights reserved.