Vapor−Liquid Equilibria and Critical Behavior of Heavy n-Alkanes Using Transferable Parameters from the Soft-SAFT Equation of State

Abstract

A new set of molecular transferable parameters for the n-alkane series is proposed. n-Alkanes are modeled as homonuclear chainlike molecules formed by tangentially bonded Lennard-Jones segments of equal diameter and the same dispersive energy. Phase equilibria calculations of heavy pure members of the series, up to n-octatetracontane (n-C48H98), and of ethane/n-decane and ethane/n-eicosane mixtures are performed with the soft-SAFT (statistical associating fluid theory) equation of state. This SAFT-type equation explicitly accounts for repulsive and dispersive forces in the reference term through a Lennard-Jones interaction potential, and it has been proven to accurately describe the phase behavior of light n-alkanes. Using the new set of parameters, the soft-SAFT equation is able to accurately predict the phase behavior of pure heavy n-alkanes. The dependence of the critical properties of pure n-alkanes with the carbon number is also predicted to be in quantitative agreement with experimental data, valida...