Mass Transfer Performance of a Capillary Microreactor during Ultrasound-Assisted Phase Transfer Catalysis

In this study, the liquid-liquid catalytic phase transfer reaction between benzyl chloride and sodium sulfide was investigated in an ultrasound-based capillary microreactor. The mass transfer performance in the multi-phase reaction was evaluated in terms of the mass transfer coefficient and was compared to the performance of other systems namely, a capillary microreactor under silent conditions, a batch reactor with different speeds of agitation, an ultrasound-assisted batch reactor, and an ultrasound-assisted batch reactor with mechanical agitation. In the batch reactor system, the mass transfer coefficient increased by a large factor when mechanical agitation was accompanied by ultrasound irradiation. However, the capillary microreactor was superior to the batch reactor system under different operation conditions. In the case of the capillary microreactor, it was found that the mass transfer performance was enhanced by a greater degree under sonication conditions than under silent conditions. Under sonication conditions, the mass transfer performance was further enhanced by increasing the aqueous-to-organic phase flow rate ratio.