The use of molecular orbital calculations to describe the phase behavior of hydrogen-bonding mixtures

In previous studies we have used Hartree-Fock theory and density functional theory to compute the enthalpy and entropy changes of dimerization Ibr methanol and a nunaber of small carboxylic acids. We have shown that by using these restdts in a physical equation of state, the statistical associating fluid theory ISAFTI. we are able to model the phase behavior of these pure hydrogen-bonding compounds with a reduction in the number of adjustable parameters: in this study, we use the pure-component parameters derived from the resuhs of our molecuhtr orbital calculations to describe the phase behavior of mixtures containing one associating and one nonassociating compound. again ttsing the SAFT eqttation of state, We show that the use of the pure-component SAFT parameters derived from our quantum-naechanical calcuhttions results in correlations of mixture VLE data with no loss of accuracy, and frequently with improved accuracy, compared to the original parameters reported Ibr use wflh the SAFT model.