The crystallization work at the institute is directed to the two general objective functions of crystallization processes:
- product design and
- separation of mixtures.
The product design in terms of getting a disperse phase of desired characteristics (e.g. a definite particle size distribution) is of special interest in case of gaining bulk crystallization products like inorganic salts and organic intermediates. In this frame the work carried out implies modelling, simulation and control of batch and continuous crystallization processes. Theoretical calculations are supported by experiments using the pilot scale crystallizer.
On the other hand crystallization methods are very powerful separation techniques. Their applicability and potential to produce pharmaceuticals, particularly pure enantiomers, is another field of interest at the Max-Planck-Institute. One focus is laid on designing a crystallization-based hybrid approach for enantioseparation in order to significantly increase the productivity for the entire process. The problem is studied on a theoretical and experimental basis using pharmaceutical relevant systems. Fundamental physical and chemical data required for crystallization purposes are determined and measurement techniques for crystallization monitoring are tested and adapted.
Various batchwise and continuously operated crystallization facilities from 50 mL up to 20 L reactor volume are applied. The reactors may be equipped with various in-, on- and offline measurement techniques to analyze temperature, solution concentration (supersaturation), enantiomeric excess, particle size etc. Reactor operation and data acquisition are supported using a process control system.
Some of the topics we deal with are the following:
- Measurement techniques for monitoring and investigation of crystallization processes,
- Solid-liquid equilibria for design and optimization of crystallization processes,
- Crystallization kinetics, particularly crystal growth,
- Crystallization-based hybrid approaches for efficient enantioseparation,
- Advanced crystallization-based enantioseparation concepts (e.g. innovative process strategies of preferential crystallization and extension of applicability, application of optically active solvents),
- Nonlinear dynamics of crystallization processes,
- Control of crystallization units.
These tasks are handled interdisciplinarily in different research groups and in cooperation with companies and universities.