RECENT ASPECTS IN SIMULATED MOVING-BED

Citation
J. Blehaut et Rm. Nicoud, RECENT ASPECTS IN SIMULATED MOVING-BED, Analusis (Imprime), 26(7), 1998, pp. 60-70
Citations number
52
Categorie Soggetti
Chemistry Analytical
Journal title
ISSN journal
03654877
Volume
26
Issue
7
Year of publication
1998
Pages
60 - 70
Database
ISI
SICI code
0365-4877(1998)26:7<60:RAISM>2.0.ZU;2-U
Abstract
Simulated moving bed (SMB) is a continuous, counter-current binary sep aration technique, more and more used in the separation of fine chemic als and pharmaceuticals. The first industrial SMB units have now been implemented in the pharmaceutical industry, for the separation of opti cal isomers. This article describes some of the most important feature s which now belong to SMB dedicated to applications in the fine chemis try: The separation of optical isomers, a very critical technical prob lem for the pharmaceutical industry is now well solved at large scale thanks to the SMB technique. MB is often not used alone, but when poss ible in coupling with enantioselective crystallization (the SMB is use d to pre-purify a crude material with a high robustness and an enhance d productivity, while crystallization is used to ''polish'' the enanti omer). Very short columns (less than 10 cm long) have been optimized t o take advantage of very small stationary phase particles now used in chromatography. For chiral separations, they allow to dramatically dec rease the overall separation process cost. Softwares play a much more important role than before: simulation tools allow to numerically opti mize the SMB parameters for nearly all kinds of molecules with a very limited number of experiments and to help validate the separation proc ess with simulated ''worst cases'', while improved control softwares a llow to circumvent some technical difficulties due to the asymmetry of SMB systems.The way to consider the SMB and the associated evaporatio n unit in a single unit operation lead to a well-defined process which may reduce the number of in-process controls and the consequences of non conformity of the product. Beside liquid SMB, this article introdu ces a more recently developed SMB process, working with supercritical eluent. This technique might find interesting applications especially in the separation of certain lipidic compounds.