Numerical Short-Cut Design of Simulated Moving Bed Chromatography for Multicomponent Nonlinear Adsorption Isotherms: Nonstoichiometric Langmuir Model

Abstract

For the fine chemical and pharmaceutical industries, simulated moving bed (SMB) chromatography is a very promising separation process. Because of its structural and operational complexity this periodically operated multicolumn process is not easy to design and optimize. In the 1990s, Storti, Mazzotti, and Morbidelli exploited the potential of the equilibrium theory and developed a now well-established short-cut design method for the conventional four-zone SMB processes. The concept, which is known as the “triangle theory”, provides explicit design rules for a small set of nonlinear adsorption isotherm models and the case of processing binary feed mixtures. For the sake of extending the triangle theory to multicomponent systems, we introduce in this work a numerical short-cut method. The iterative method will be illustrated to design a conventional four-zone SMB process for the separation of quaternary mixtures obeying nonstoichiometric Langmuir isotherms. The results will be validated by comparing predicted internal concentration profiles with the results of additionally carried out true moving bed simulations.

Shortcut design method for multicomponent gradient simulated moving beds

“…[27][28][29][30] For nonconstant selectivity, the lines for constructing the triangular diagram can be determined numerically. 6,16,18,24 3 | METHODS…”

“…Since then, the SMB have successfully been applied in a wide range of separations such as p-xylene from C 8 -isomers, fructose from corn syrup, enantioseparations etc. 3,4,6 For batch chromatography, applying a gradient in elution strength is common, and can increase productivity as well as enable complete separation. 1,2 Likewise, the utilization of a gradient to enhance separation performance can be implemented in a variant of SMB known as gradient SMB.…”

“…16,17 These shortcut design methods can reduce the complexity and the computational efforts to determine optimal operating conditions for the SMB. 6,[16][17][18] Migliorini et al 16 proposed a versatile shortcut design method applicable to any isotherm; however, the application of the method to gradient SMB or multicomponent systems is less clear. Instead, the focus is on the isocratic operation of the SMB.…”

“…One way of running chromatography continuously is a simulated moving bed (SMB) which was invented in the 1960s. Since then, the SMB have successfully been applied in a wide range of separations such as p‐xylene from C 8 ‐isomers, fructose from corn syrup, enantioseparations etc 3,4,6 …”

“…These constraints allow for the computation of operational flow rate ratios for each TMB section, which can then be transformed into SMB flow rates 16,17 . These shortcut design methods can reduce the complexity and the computational efforts to determine optimal operating conditions for the SMB 6,16–18 …”