Measurements of the phase behavior of ternary systems of interest to the GAS process: III. The system CO2 + toluene + naphthalene

Systems consisting of a supercritical gas, an organic solvent and an organic solute are of interest for the gas-antisolvent (GAS) process. In this work the phase behavior of the ternary system carbon dioxide + toluene + naphthalene was studied in a Cailletet apparatus over the temperature range 283–343 K and pressures varying between 2 MPa and 12 MPa. The system was investigated by means of a quasi-binary approach, in which the carbon dioxide mole fraction was kept constant. For three different mole fractions of carbon dioxide (0.3, 0.5 and 0.8) five different naphthalene/toluene ratios were added to give a certain overall composition. Additionally a mixture containing 77.5 mol% carbon dioxide, 9.5 mol% toluene and 13 mol% naphthalene was studied. The experimental data show that in the ternary system carbon dioxide + toluene + naphthalene complex multiphase behavior occurs.

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► The system CO2 + toluene + naphthalene was studied in a Cailletet apparatus.
► The temperature range was 283–343 K and the pressure range 2–12 MPa.
► Almost the whole ternary composition range was studied (16 compositions).
► Complex phase behavior was observed including 2-, 3- and 4-phase equilibria.