Modeling of Simultaneous Chemical and Phase Equilibria in Systems Involving Non-reactive and Reactive Azeotropes

Abstract

Simultaneous chemical and phase equilibrium (CPE) calculations are essential in chemical engineering, finding numerous applications in industrial processes, such as reactive distillation. CPE calculations can be challenging in systems involving polar and associating components, which also exhibit azeotropes or even reactive azeotropes, with two common examples being methyl tert-butyl ether and isopropyl acetate synthesis systems. To tackle the problem, a robust algorithm for solving CPE is required, coupled with an accurate thermodynamic model for describing system nonideality. In this work, a Gibbs energy minimization algorithm based on the method of Lagrange multipliers is employed for performing CPE calculations in the aforementioned systems. The algorithm is coupled with traditional activity coefficient models UNIQUAC and UNIFAC, as well as the UMR-PRU model. The results indicate that all models can successfully describe the CPE in the studied systems. UMR-PRU yields very satisfactory results, despite being utilized as a purely predictive tool.

Simultaneous Predictions of Chemical and Phase Equilibria in Systems with an Esterification Reaction Using PC-SAFT

“…Non-stoichiometric methods directly attempt at solving the optimization problem given by Equations (1)–(4), using for instance the Kuhn–Tucker necessary conditions for minimization. Stoichiometric methods avoid the element balance constraints (Equation (2)) by formulating the component balance as a linear combination of reaction coordinates , according to Equation (5) [ 60 ]. …”

“…The RAND algorithm is nowadays employed in commercial software such as Aspen Plus [ 59 ]. Recently, Koulocheris et al [ 60 ] published an algorithmic approach to perform CPE of reactive VLEs using traditional G E -models and tested their approach to several systems containing azeotropes. For an extensive discussion on the different available algorithms, we refer to the recent literature [ 53 , 61 , 62 , 63 ].…”

“…The number of phases and initial composition estimates are provided by the tangent plane stability analysis [ 84 , 85 ]. Although the general idea of the double-nested procedure is widely known (see, for instance, [ 54 , 57 , 60 , 86 , 87 , 88 ]), in this work, we proposed some new ideas to improve the robustness of the CPE calculation. The algorithm was applied to predict the CPE of two quaternary systems with an esterification reaction and the modeling results were compared with experimental data from the literature.…”

Vapor-Liquid and Chemical Equilibrium for Esterification of Acetic Acid + Isopropanol with [HSO3 -bmim][HSO4 ] at 101.33 kPa

“…Chemical and phase equilibrium (CPE) data are critical for the study and simulation of reactive distillation, it provides effective thermodynamic data for the design and optimization of the reactive distillation process [20][21][22][23]. CPE data of ethanol + ethanoic acid [24], acetic acid + butan-1-ol [25], and acetic acid + 2-propanol systems have been reported [26].…”