New Generalization of Cohesion Factor Model for Polar Compounds: Peng-Robinson Equation of State

Abstract

Predicting physical properties is one of the major requirements in process engineering. Equations of state (EoS) are widely used for predicting physical properties. Among many EoS, cubic equations of state (cubic EoS) are being used because they are simple and applicable over a wide range of temperature and pressure. However, these cubic EoS fail to predict properties of a compound having polarity, association as well as hydrogen bonding. In the present study a new generalization for cohesion factor, to be used with Peng-Robinson (PR) EoS was proposed. In developing the model, compound-specific parameters for nearly 300 compounds were generated. These compound-specific parameters were correlated in terms of the reduced dipole moment and critical compressibility factor. Proposed models were compared with models available in the literature. Vapor pressure, heat of vaporization, saturated liquid density and second virial coefficient of the compounds were predicted. It was observed that the models with reduced dipole predicted various properties accurately for highly polar compounds without losing accuracy in predicting properties for non-polar compounds.