• Denayer, Joeri
• Rubiera Landa, Héctor Octavio

Abstract

An Efficient Implementation of Maxwell-Stefan Theory for Modeling Gas Separation Processes<br/>Héctor Octavio Rubiera Landa, Joeri F. M. Denayer<br/>Department of Chemical Engineering and Industrial Chemistry, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Elsene, Brussels, Belgium<br/><br/>Separation process modeling of fixed-bed adsorbers and thin-layered membranes consists typically of macroscopic mass and energy balances, with simplifying principles to be able to describe mass transfer processes at the particle level (i.e., lumped-kinetics models). However, for several gas separation processes, such as kinetically-controlled adsorption and membranes, the dynamics of the microscopic scale occur very slowly, and a detailed description of mass transfer is unavoidable for their accurate description. The Maxwell-Stefan Theory (M-S) is a powerful approach based on the principle of Irreversible Thermodynamics applied to describe diffusion processes at the microscopic level (i.e., particles, crystals) [1,2]. It has been employed for modeling fixed-bed adsorbers with slow kinetics and membrane processes [3]. The M-S approach requires a competitive adsorption equilibria ansatz for its application. In this work, we present a computationally efficient formulation that implements the M-S approach for these kinds of gas separations by applying the thermodynamically-consistent Ideal Adsorbed Solution Theory (IAST) [4]. We formulate transient mass balances as systems of Differential-Algebraic Equations (DAEs) that result from applying a Method of Lines Approach (MOL) for their numerical solution. IAST is incorporated in this solution principle by applying an accurate calculation approach developed in [5,6]. The advantages and robustness of the developed solution method are illustrated with several examples for describing particle adsorption dynamics and transport in thin-layered membranes.<br/>References:<br/>[1] R. Krishna, Chemical Engineering Science 45(7), 1779–1791 (1990).<br/>[2] J. Kärger, D. M. Ruthven, D. N. Theodorou, Diffusion in Nanoporous Materials, Wiley (2012).<br/>[3] R. Krishna, Microporous and Mesoporous Materials 185, 30–50 (2014).<br/>[4] A. L. Myers, J. M. Prausnitz, AIChE Journal 11(1), 121–127 (1965).<br/>[5] H.O. Rubiera Landa, D. Flockerzi, A. Seidel-Morgenstern, AIChE Journal 59(4), 1263–1277 (2013).<br/>[6] H.O. Rubiera Landa, J. F. M. Denayer, in preparation (2023).

Topics

• impedance spectroscopy
• theory
• layered