Fluid-Phase Equilibrium Experiments and Modeling for\nCO<sub>2</sub> + C<sub>6</sub> Binary Systems

The phase behavior of the carbon\ndioxide and <i>n</i>-hexane binary mixture was examined.\nThe entire available literature\nwas reviewed and analyzed. Despite the apparent abundance of experimental\ndata, both vapor–liquid equilibrium (VLE) and critical data,\nthere is a high degree of discrepancy between them. Therefore, the\nliquid–vapor critical line was determined up to 117.0 bar and\n383.15 K, as well as VLE data at different constant temperatures (313.15\nto 383.15 K) using a 60 cm<sup>3</sup> stainless-steel cell with sapphire\nwindows connected to a gas chromatograph via rapid online sample injectorsROLSI\nvalves for accurate composition detection. The new and literature\ndata were successfully calculated with several models (General Equation\nof stateGEOS, Peng–RobinsonPR, and Soave–Redlich–KwongSRK),\nin association with classical van der Waals mixing rules, i.e., one-\n(1PCMR) and two-parameter conventional (2PCMR) combining rules, as\nwell as the PPR78 model. We also studied the influence of the structure\nof organic compounds (<i>n</i>-alkane, cycloalkane, and\nbranched alkane-position isomers) with the same number of carbon atoms\non the phase behavior of their corresponding binary systems at high\npressures.