High-pressure Vapor-Liquid Equilibrium Studies for DME-CO2-CH3OH and DME-CO2-C2H5OH Systems1

In this study, the Gibbs-Duhem equation was applied to make the thermodynamic consistency test and thermodynamic model estimation for systems of CO2-DME (dimethyl ether), DME-CH3OH, CO2-CH3OH and C2H5OH systems on the basis of the vapor-liquid equilibrium (VLE) experimental data in published reports. And the NRTL binary interaction parameters of the systems mentioned above were regressed by the VLE data and were subjected to a thermodynamic consistency test because the study showed that PR-NRTL model combination was appropriate for the four systems mentioned above. The regressed binary interaction parameters were used to estimate the VLE for DME-CO2-CH3OH at temperatures of 313.15K and 333.15K, and the estimated result was coincident with the experimental data. On the basis of the predicted VLE data for systems of DME-CO2-CH3OH and DME-DME-CO2-C2H5OH, the VLE behaviors of the two systems were studied by the phase diagrams of these two ternary systems, with the forms of both the two dimensional and three dimensional phase diagrams, respectively.