Isobaric vapor–liquid equilibrium for binary systems of toluene + o-xylene, benzene + o-xylene, nonane + benzene and nonane + heptane at 101.3 kPa

• Isobaric vapor–liquid equilibrium (VLE) data were measured at 101.3 kPa.
• Toluene + o-xylene, benzene + o-xylene, nonane + benzene, and nonane + heptane were studied.
• No azeotrope formed in the systems investigated.
• The VLE data were correlated well with the Wilson, NRTL, UNIQUAC models and SRK equation of state.
• The predictions from the UNIFAC and the COSMO-RS were compared with the VLE data.

Isobaric vapor–liquid equilibrium (VLE) data for the binary systems of toluene + o-xylene, benzene + o-xylene, nonane + benzene and nonane + heptane were measured at 101.3 kPa by using a modified Othmer still. The thermodynamic consistency of these new VLE data was checked by using the point to point test of Van Ness. No azeotrope was found in these binary systems investigated. While nonane + benzene were found to have large positive deviation, toluene + o-xylene, benzene + o-xylene, and nonane + heptane exhibited large negative deviation from ideal behavior. The binary interaction parameters of the Wilson, the NRTL, the UNIQUAC models and the SRK equation of state for these four binary systems were determined through the VLE data reduction. These new VLE data were compared with the predicted values from the UNIFAC and the COSMO-RS (conductor-like screening model for realistic solvents) models as well. Generally, reasonable agreement was found between the predicted results and the experimental values, except for nonane + benzene system.