(115c) The Intermittent Simulated Moving Bed (I-SMB) Process

Simulated Moving Bed (SMB) chromatography has become one of the key techniques in pharmaceutical industry to separate enantiomers and over the last decade several modified SMB schemes have been proposed in order to improve productivity yet guaranteeing high purity specifications enforced by regulatory agencies such as the Federal Drug Agency and the European Medicines Agency.

The Intermittent SMB (I-SMB) process is one of such modifications being applied in the sugar industry [1]. The switch time is divided into two sub-intervals; in the first interval, the unit is operated as a conventional SMB, with two inlet streams (feed and desorbent) and two outlet streams (extract and raffinate), however, no flow in section four; in the second one, the inlet and outlet ports are closed and the flow is just circulated within the column train. This operation mode allows to move the concentration profiles along the columns and to adjust their relative position with respect to the outlet ports. In a recent study, we demonstrated experimentally the performance of the I-SMB process under linear conditions as well as through simulations. The four-column I-SMB achieved the same high purities as the standard six-column SMB, while improving at the same time the process productivity substantially [2].

This work presents the concept of the I-SMB process and analyzes its performance under non-linear operating conditions, i.e. at high feed concentrations. Experimental results are obtained for the separation of Tröger's base enantiomers using Chiralpak AD as stationary and Ethanol as mobile phase. The experiments are carried out using the I-SMB and the standard SMB configuration in order to compare the two processes in terms of productivity and solvent consumption. The obtained experimental results are presented together with simulation results. The findings demonstrate that due to the partial feed and withdrawal operation the I-SMB achieves superior performance compared to the conventional SMB.

[1] M. Tanimura, M. Tamura, T. Teshima, Japanese Patent JP-B-H07-046097 (1995)

[2] S. Katsuo, M. Mazzotti, Presented at SPICA2008, Zurich, Switzerland, 2008.