Cooling Crystallization Using a mL-Scale Continuous Crystallizer Equipped with a High Speed Agitator for Production of Uniform Small Crystals

摘要

A mL-scale continuous crystallizer has been newly developed to produce small crystals with a narrow size distribution. The crystallizer is composed of a stainless-steel mixing vessel with an inner working volume of 7.9 mL and a high-speed agitator that can agitate the crystallization solution at up to 24,000 rpm. In a previous work, the crystallizer was used for the drowning-out crystallization of glycine and L-alanine. The crystals obtained with the novel crystallizer were small and uniform in size, comparing with those obtained with conventional beaker-scale semi-batch and continuous MSMPR type crystallizers. In this study, the cooling crystallization of L-alanine was attempted using the mL-scale crystallizer. The undersaturated hot solution of L-alanine and the water-immiscible coolant liquid were introduced into the crystallizer and were intensely agitated. The solution was dispersed as small droplets into the coolant liquid and rapidly cooled. The crystals obtained by the mL-scale cooling crystallizer are small and uniform in size as well as the drowning-out crystallization.