New Advances in the Modeling and Verification of Experimental Information for Ester-Alkane Solutions: Application to a Batch-Distillation Case

Abstract

This work shows a practical experience involving the following sequence of tasks on eight binary solutions of alkyl (propyl, butyl) propanoate with four alkanes (hexane to nonane): experimentation → modeling ↔ verification → simulation. Thermodynamic properties related to dilution processes are determined, in addition to vapor-liquid equilibria at 101.32 kPa (iso-p VLE), providing a vast database. Some improvements are proposed for the aforementioned tasks: (a) density values at high temperature and pressure for the pure compounds and their modeling to improve the calculation of activity coefficients, (b) the procedure of multiproperty modeling using an ϵ-constraint multiobjective procedure combined with a genetic algorithm for mixed integer nonlinear problem (MINLP) problems, obtaining a {data + model} set, which is subjected to the third task of thermodynamic validation, and (c) with the methodology established in Wisniak, J. et al. A Fresh Look at the Thermodynamic Consistency of Vapour-Liquid Equilibria Data. J. Chem. Thermodyn. 2017, 105, 385 395, the consistency of iso-p VLE data was confirmed, and the process was assisted by a modification of our own method to guarantee the {model-checking} binomial, increasing the reliability of the experimental data provided and the model obtained. The systems propyl propanoate-octane and butyl propanoate-nonane are azeotropic with coordinates, respectively, at (xaz = 0.650; Taz/K = 392.4) and (xaz = 0.633; Taz/K = 417.1). The model obtained for the first system is used to simulate the separation process of that binary with a commercial simulator. After implementing the model, comparison of the results generated by the software produced values close to real ones obtained in a batch distillation in the laboratory, improving the values estimated by the simulator software.