Optimal Determination of the Binary Interaction Parameters for the Vapor-Liquid-Liquid Equilibrium on the Vinyl Acetate/Acetic Acid/Water System

The design of the vinyl acetate purification process requires modelling the vapor-liquid-liquid equilibrium (VLLE) of the mixture vinyl acetate/acetic acid/water. In this work, the equilibrium of the system is represented through the gamma-phi formulation using the Hayden O'Connell (HOC) model for the vapor phase and the universal quasi-chemical (UNIQUAC) model for the liquid phases. The parameters for the model are estimated through optimization tools, using the BARON global optimization algorithm. The objective function to be minimized was the least-squares function. The results show a good correlation for the LLE and VLE of vinyl acetate with water with errors less than 2%. In the case of the VLE equilibrium of water with acetic acid the error is close to 5% with a larger deviation at acid mole fractions above 0.4. The parameters determined allow a proper modeling of the VLLE for the analyzed mixture.