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.