PHASE-EQUILIBRIUM STUDY FOR THE SEPARATION OF ETHANOL WATER SOLUTION USING SUBCRITICAL AND SUPERCRITICAL HYDROCARBON SOLVENT-EXTRACTION

In order to dehydrate fermented or synthetic crude ethanol, phase equilibria for subcritical and supercritical solvents (CO2, C2H4, C3H6, C3H8, n-C4H10 and CO2 + C3H8) and ethanol aqueous solution (ethanol concentrations of 2-99 wt.%) were measured. For these solvents the selectivity and solubility of ethanol under different conditions were investigated. We confirmed experimentally that ethanol-water solution can be separated completely by supercritical and subcritical propane or proylene solvent extraction, as has been predicted previously using the group contribution equation of state model proposed by Brignole et al. (Brignole, E.A., Skjold-Jorgensen, S. and Fredenslund, A., 1984. Ber. Bunsenges. Phys. Chem., 88: 801. Brignole, E.A., Anderson, P.M. and Fredenslund, A., 1987. Ind. Eng. Chem. Res. 26: 254-261.)