Isobaric Vapor–Liquid Equilibrium of the Binary Mixtures Toluene + Styrene and Styrene + α-Methylstyrene

Isobaric vapor–liquid equilibria of the binary mixtures toluene + styrene at 30 and 40 kPa and styrene + α-methylstyrene at 20 and 25 kPa were measured applying a recirculation still. The measured vapor–liquid equilibrium data were modeled adopting the non-random two-liquid (NRTL) excess Gibbs energy model with the RK (Redlich–Kwong) equation of state. The NRTL binary interaction parameter optimization was carried out employing own measured data and literature data for the toluene + styrene system. The applied model correlates well with the experimental data at the pressure range of 101–30 kPa. Moreover, the NRTL binary parameter regression was performed applying own measured data and literature data separately for the styrene + α-methylstyrene system. The model fitted with the parameters obtained from own measured data described the multiphase behavior of the system better than the parameters obtained from literature data. Additionally, the binary systems showed ideal behavior over the whole range of investigation as the calculated activity coefficients approached unity and no azeotropes were observed.