Ternary-phase equilibria for CO₂ + 3-methyl-1-butanol + 2-phenylethanol

Studies of wine and wine must fractionation by supercritical carbon dioxide have shown that 3-methyl-1-butanol and 2-phenylethanol are aroma compounds present in sizeable amounts in the extracts. Ternary vapour-liquid equilibrium diagrams for CO₂ + 3-methyl-1-butanol + 2-phenylethanol were measured at 313 K and at three different pressure values: 7, 10 and 15 MPa. They were correlated with the Peng-Robinson equation of state. The most striking feature of these data is the large effect of pressure on the separation factors between phases of the two aroma substances. Liquid-liquid-vapour three-phase coexistence boundaries in the pT diagram were also measured, from 287 to 315 K. A few experiments of fractionation with CO₂ of a mixture of 3-methyl-1-butanol + 2-phenylethanol were carried out in a countercurrent column. The results were interpreted on the basis of the phase equilibrium data.