Isobaric Vapor-Liquid Equilibrium Prediction from Excess Molar Enthalpy Using Cubic Equations of State and PC-SAFT

Vapor-liquidequilibrium (VLE) data, essentialfor an accurate design of distillation columns, are not always readilyavailable. This work has systematically assessed the feasibility ofdetermining VLE data based on excess molar enthalpy(h ( E )) results. Twelvecubic Equation of State (cEoS) models combined with eight mixing rulesand the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT)have been assessed. cEoS models are robust and applicable to a significantnumber of solvent families, while the PC-SAFT model is typically appliedfor strongly nonideal systems exhibiting molecular association behavior. VLE predictions based on the Peng-Robinson cEoS withthe 2-parameter Stryjek-Vera-Margules-type mixing rule,one of the best cEoS-mixing rule combinations, was reasonablyaccurate, but less accurate than predictions based on the standardmodified (mod.) UNIFAC (Do) model. This makes the developed h ( E )-cEoS-VLE methodology relevant only for systems whose binaryinteraction parameters in UNIFAC (Do) and VLE dataare not available. For the most nonideal self-associating systemsevaluated, the PC-SAFT model parametrized with experimental h ( E ) data provided isobaric VLE results with similar or even higher accuracy than themod. UNIFAC (Do) model. This indicates the potential of the h ( E )-PC-SAFT-VLE model for accurately predicting VLE data for highly nonideal and associating systems. Therefore, thismethodology can be used as a quick evaluation method for the separationof complex systems, including ionic liquids and deep eutectic solvents,for which the mod. UNIFAC (Do) model does not provide sufficientlyaccurate VLE predictions.