The Sanchez–Lacombe lattice fluid model for the modeling of solids in supercritical fluids

The Sanchez–Lacombe equation of state is known to describe the thermodynamic properties of molecular fluids of arbitrary size, especially polymer–solvent phase behavior. However, it is rarely used for modeling solid–supercritical fluid equilibria. In this work, it is shown that a proper estimation of the EoS characteristic parameters together with a thermodynamically consistent expression of fugacity coefficients allows a satisfactory correlation of the solubility of solids in the supercritical phase. Binary mixtures containing carbon dioxide, ethane, ethylene and xenon were considered for this purpose. In a first step, the consistency of experimental data was checked using variance analysis. Then, different mixing rules were considered and results compared with those obtained with the Peng–Robinson equation. Finally, the lower and upper boundaries of the solid–liquid–vapor regions (LCEP and UCEP) were also determined and compared with experimental values.