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Abstract

Simulated Moving Bed (SMB) chromatography is a well-established process for the separation of binary mixtures. However, multicomponent mixtures are more likely to be encountered in reality. Various modifications of the classical SMB systems have been proposed (e.g. [1,2,3]) due to the increasing interest in isolating target components out of multicomponent feed mixtures and the inability of conventional 4-zone SMB systems to produce pure product streams if the targets are neither the strongest nor the weakest adsorbable components. In the work to be presented a real separation problem is investigated using advanced SMB technology. Analyzed ternary mixture consists of three cycloketones: cyclopentanone (C5), cyclohexanone (C6) and cycloheptanone (C7). Single component as well as competitive adsorption isotherms were determined experimentally using peak fitting method at ambient temperature. Also determined experimentally van Deemter relation between column plate height and mobile phase velocity was implemented in theoretical calculations. Theoretical analysis of the separation problem includes detailed study of six different SMB configurations capable to purify and produce the component with intermediate adsorption strength (C6). Analyzed are two coupled 4-zone SMB units connected in series via the extract or raffinate port, each unit operated with individual switching time. These units can be operated either in continuous or semi-continuous mode, where in latter case separation can be performed in two steps using only one conventional 4-zone SMB system. Subsequently, the performance of these configurations is compared to an integrated 8-zone unit with internal recycle of extract or raffinate stream operated with one switching time for the whole unit. The performance of each configuration is analyzed and compared at optimal conditions in terms of productivity and outlet concentration of target product as well as specific desorbent consumption and desorbent to feed ratio. To describe the performance of consider ed arrangements a standard dynamic model was applied. A pilot scale experimental set-up recently developed in our laboratory, capable to realize in practice the separation of ternary mixture based on 8-zone SMB configuration with internal recycle will be introduced. With such a modified system three component separations are possible with only one integrated system. The status of the experimental realization of investigated separation problem will be presented. [1] P.C. Wankat, Ind. Eng. Chem. Res. 40 (2001) 6185 [2] R.-M. Nicoud, SMB Chromatography for Biomolecules, Academic Press, San Diego, CA, 2000. [3] L.C. Kessler, A. Seidel-Morgenstern, J.Chromatogr. A 1126 (2006) 323