Prediction of Mutual Solubilities of Heavy Components with Super‐Critical and Slightly Sub‐Critical Solvents: The Role of Equations of State and Some Applications of a Simple Expanded Lattice Model at Subcritical Temperatures

Abstract

Abstract The use (and limitations) of equations of state for collating and predicting liquid/liquid and liquid/dense fluid equilibria is discussed with reference to 15 binary pairs (including some new data for the Carbon dioxide/Hexadecane system at 60°C) and three ternary combinations. It is concluded that the estimation of some of the parameters required for these calculations would be difficult if the solute was a complex substance about which little was known apart from its structural formula. ‐ An alternative procedure is to apply activity coefficient expressions of the “regular solution” or UNIFAC type to each phase. Preliminary calculations along these lines are described and the physical basis for applying these methods under the relevant conditions is discussed. The “UNIFAC” approach in particular has been found to be encouraging, though the interaction parameters must be regarded as pressure dependent.