A novel batch cooling crystallizer for in situ monitoring of solution crystallization using energy dispersive X-ray diffraction

In situ X-ray diffraction monitoring of crystallization from solution is often hampered by a combination of the rather low levels of crystallized solid (typically 5 to 20 wt %) and the large background scattering that arises from the solution phase. In this work, we have attempted to overcome these limitations, first, by using high intensity dispersive X-rays available at the Synchrotron Radiation Source, Daresbury Laboratory, UK, and second by designing a novel batch classifying crystallizer. This crystallizer was designed to maximize the weight fraction of solid presented to the probe beam. In this configuration, solution crystallizations generating between 2 and 30 wt % of solids were monitored successfully. Three preliminary studies describe the application of this equipment to the simple real time monitoring of a crystallization event, the interconversion of two polymorphic crystalline forms, and the orientation of crystals in the fluid flow of the crystallizer.