On-line optimization of four-zone simulated moving bed chromatography using an Equilibrium-Dispersion Model: II. Experimental validation

Abstract

In the first theoretical part of this work, an on-line optimization method using the equilibrium-dispersion model of chromatography was developed for the dynamic optimization of periodically operated four-zone simulated moving bed (SMB) processes. In this second part, we present the experimental validation of the proposed concept. To describe the behaviors of real SMB systems, the on-line control unit was modified. Unavoidable system void volumes, which can be described using delay functions corresponding to standard mass balance models for pipes and CSTs, were considered in addition to the chromatographic columns. Furthermore, a new sample collection method that does not interrupt product streams was introduced for process monitoring. The equipment including an external concentration analysis unit was automated via a tailor-made interface program. The on-line control unit estimated the parameters of the process model and optimized the future operating conditions ‘switch-by-switch’. The case study investigated in this work was the separation of racemic mixtures of two bicalutamide enantiomers using a chiral stationary phase applying the conventional and two advanced SMB operating modes.