Thermodynamic properties of mixtures of kihara molecular fluids from perturbation theory

A perturbation theory for mixtures of molecules interacting through the Kihara potential is proposed. We show that the Kihara potential with the Lorentz-Berthelot combination rule to describe the crossed interaction is able to give very good results for the excess properties of different mixtures. The results obtained by using the Kihara model are comparable to or even better than those obtained with the more popular site-site model. We have applied the theory to several mixtures of hydrocarbons involving different geometries, such as methane+ethane, methane+propane, ethane+propane, methane+isobutane, ethane+isobutane, and propane+benzene