Continuous flow synthesis of ZSM-5 zeolite on the order of seconds

Significance Zeolites have greatly contributed to modern industries. Consumption of zeolites is expected to increase with the emergence of newly commercialized applications. Typical synthesis of zeolites relies on batchwise hydrothermal synthesis, which usually takes tens of hours or even several days to complete. People have thus long believed that the crystallization of zeolites is very slow in nature. We herein demonstrate the continuous flow synthesis of ZSM-5, an industrially important zeolite, on the order of seconds. Crystallization from amorphous state to full crystallinity could be completed in tens of or even several seconds. The synthesis on the order of seconds provides a great potential to facilitate the mass production as well as to deepen the fundamental understanding of zeolite crystallization. The hydrothermal synthesis of zeolites carried out in batch reactors takes a time so long (typically, on the order of days) that the crystallization of zeolites has long been believed to be very slow in nature. We herein present a synthetic process for ZSM-5, an industrially important zeolite, on the order of seconds in a continuous flow reactor using pressurized hot water as a heating medium. Direct mixing of a well-tuned precursor (90 °C) with the pressurized water preheated to extremely high temperature (370 °C) in the millimeter-sized continuous flow reactor resulted in immediate heating to high temperatures (240–300 °C); consequently, the crystallization of ZSM-5 in a seed-free system proceeded to completion within tens of or even several seconds. These results indicate that the crystallization of zeolites can complete in a period on the order of seconds. The subtle design combining a continuous flow reactor with pressurized hot water can greatly facilitate the mass production of zeolites in the future.