Molecular models of unlike interactions in fluid mixtures

Abstract

Recently published molecular models of two-centre Lennard–Jones plus pointquadrupole type for pure fluids are used for the quantitative description of vapour–liquid equilibria of 28 binary mixtures. The unlike interactions are described with a modified Lorentz–Berthelot combining rule that contains one binary interaction parameter in the energetic term. A recently published simple and efficient procedure is used to adjust the binary interaction parameter to a single experimental vapour pressure of the binary mixture. Vapour–liquid equilibria from these molecular models for binary mixtures are in good agreement with experimental data also at state points far away from those used for the parameter fit. Vapour–liquid equilibria of ternary mixtures are predicted reliably on that basis.

Keywords:

• Molecular models
• Mixtures
• Unlike interactions
• Vapour–liquid equilibria

Acknowledgements

The authors thank Tobias Günther for his literature and simulation work. We gratefully acknowledge financial support by Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 412, University of Stuttgart.