Partial miscibility behavior of the ternary mixture carbon dioxide plus n-tetradecane plus methanol

The liquid-liquid-vapor (llg) partial miscibility behavior of the mixture c arbon dioxide + n-tetradecane + methanol was experimentally studied by use of a visual cell (stoichiometric) technique. Phase compositions and molar v olumes of the two liquid phases in equilibrium are reported as functions of temperature and pressure within the llg region. The addition of the cosolv ent methanol extends the three-phase llg region in pressure-temperature spa ce from the binary carbon dioxide + n-tetradecane llg locus downward in pre ssure, toward the vapor pressure curve of the cosolvent methanol. The three -phase region is bounded from above by an upper critical end point (l-l=g) locus, which extends from the binary llg locus to a lower critical end poin t (l=l-g) locus, which bounds the region at lower pressures. The cosolvent methanol significantly enhances the amount of the solute tetradecane presen t in the second (carbon-dioxide-rich) liquid phase.