Phase equilibria for the mixtures of supercritical methanol+C18 methyl esters and supercritical methanol plus α-tocopherol

Phase equilibrium data for methanol + C18 methyl esters and methanol + alpha-tocopherol were measured at 523-573 K in the pressure ranges of 2.45-11.45 MPa for C18 methyl esters and 3.19-15.02 MPa for alpha-tocopherol, respectively. The measured data were correlated using Peng-Robinson equation of state (PR EOS) with conventional mixing rules. The distribution coefficients of C18 methyl esters and a-tocopherol in methanol were discussed. The data illustrate that when the pressure is lower than the critical pressure of methanol (8.097 MPa), the mole fractions of methanol in vapor are very close to unity for both systems. When the pressure increased over 8MPa, the distribution coefficients increased significantly for C18 methyl esters at 548-573 K and for alpha-tocopherol at 573 K. Noticeably, this work firstly reports the phase equilibrium data of C18 methyl esters in methanol at high temperatures and pressures. (C) 2008 Elsevier B.V. All rights reserved.