Optimal operation of enantioseparation by batch-wise preferential crystallization

This article describes batch-wise preferential crystallization separation of mixtures of L- and D-threonine. The use of online polarimetry combined with refractometry and microscopic investigation of the solid phase provides information on the crystallization kinetics. Results obtained for different crystallization conditions (supersaturation, temperature and enantiomeric excess) in a batch crystallizer are presented. Based on these results, a non-linear dynamic model has been developed. The control problem is to determine an optimal temperature profile which will result in a maximum amount of product with required quality. In this dynamic optimization problem B-splines have been used for interpolation of the temperature profile.