Phase Equilibrium Calculations in Mixtures Containing Caprolactam with a UNIFAC Model

An extended liquid-liquid equilibrium (LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam. In this model, caprolactam is introduced as a new group. New group interaction parameters are calibrated from 156 sets of liquid-liquid equilibrium data. The present model gives satisfactory correlation and prediction in liquid-liquid equilibrium, including quaternary systems containing the mixed solvent of an alcohol and an alkane. The model can be applied to predict caprolactam solubility in water and benzene accurately. Freezing point and vapor-liquid equilibrium of binary systems containing caprolactam are also predicted with the extended LLE UNIFAC model. Satisfactory prediction results are obtained.