New apparatus for the fast determination of high-pressure vapor-liquid equilibria of mixtures and of accurate critical pressures

An apparatus based on the static-analytic method has been designed to perform fast determinations of vapor-liquid equilibria and critical pressures for mixtures up to 60 MPa and 523 K. Vapor pressures of isobutane and vapor-liquid equilibria of the following mixtures-carbon dioxide + ethanol at (312.82, 313.15, 333.82, 333.75, 348.4, and 373.00) K up to 14.3 MPa and carbon dioxide + 2-propanol at (324.99, 324.70, 333.70, 333.82, and 348.65) K up to 10.5 MPa-are reported herein over the whole range of compositions. The experimental data are represented/predicted using the Patel-Teja equation of state (EOS) with new Wong-Sandler type mixing rules. For the carbon dioxide + ethanol and carbon dioxide + 2-propanol mixtures, the parameters of the EOS were fitted to the VLE data at 313.15 K and at 324.70 K, respectively. VLE data at higher temperatures were then predicted and found to be in good agreement with the data reported in this work. Critical pressures and compositions were also determined for the system carbon dioxide + ethanol at 312.82, 333.75, 333.82, 348.40, and 373.00 K; all of them are in agreement with those published in the literature.