Isothermal vapor-liquid equilibria at 333.15 K, 343.15 K and 353.15 K far four binary mixtures of hexane + heptane, heptane + octane, cyclohexane + octane and cyclohexane + nonane have been obtained at pressures ranged from 0 to 101.3 kPa. The NRTL, UNIQUAC and Wilson activity coefficient models have been employed to correlate experimental pressures and liquid mole fractions. The non-ideal behavior of the vapor phase has been considered by using the Soave-Redlich-Kwong equation of state in calculating the vapor mole fraction. Liquid and vapor densities were also measured by using two vibrating tube densitometers. Phase behaviors of the P-x-y diagrams indicate that three mixtures of hexane + heptane, heptane + octane, cyclohexane + octane were close to the ideal solution. However, the cyclohexane + nonane mixture presents a large positive deviation from the ideal solution. Only the cyclohexane + octane mixture is negative in the excess Gibbs energy indicates that it is an exothermic system. (C) 2009 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS