HPHT data for CO 2 with two structurally distinct naphthenes. Bicyclohexyl reduces CO 2 miscibility, shifting transitions to higher pressures. Molecular compatibility governs melting-point depression in both mixtures . The phase behavior of two asymmetric ternary systems involving carbon dioxide, naphthenic hydrocarbons, and a heavy aromatic compound was investigated experimentally. The systems studied were CO 2 + butylcyclohexane + o -terphenyl and CO 2 + bicyclohexyl + o- terphenyl. The selection of butylcyclohexane and bicyclohexyl, representing a branched monocyclic and a bicyclic naphthene, respectively, enables an evaluation of how molecular structure influences phase equilibria in CO 2 -asymmetric mixtures. The presence of o -terphenyl introduces a high-melting-point aromatic component, enabling analysis of crystallization phenomena and solid-fluid transitions. Fluid-fluid phase equilibria, including liquid-vapor and liquid-liquid transitions, were measured over a temperature range from 273 to 373 K. In addition, solid crystallization transitions were determined at pressures up to 90 MPa. The effect of carbon dioxide concentration was examined across molar fractions ranging from 0 to 90 mol%.
Vera et al. (Sun,) studied this question.