Characterization of Mixing Performance in a Microreactor and its Application to the Synthesis of Porous Coordination Polymer Particles

Abstract

Here we quantitatively evaluated the mixing performance of a tailor-made microreactor with central-collision type through the iodide/iodate chemical test reaction, and applied the microreactor to the synthesis of zeolitic imidazolate framework-8 （ZIF-8）, which is a subclass of porous coordination polymers （PCPs） or metal organic frameworks （MOFs）. The chemical test reaction demonstrated excellent mixing performance of the microreactor with a characteristic mixing time shorter than 1 millisecond, which is approximately 100 times faster than those of a batch reactor and a millimeter-sized Y-shaped mixer. Taking advantage of the rapid and uniform mixing, the microreactor successfully produced ZIF-8 particles with high reproducibility by simply mixing aqueous solutions of zinc nitrate and 2-methylimidazole. The synthesis at room temperature resulted in ZIF-8 particles with chamfered cube shape, while a lower temperature of 5℃ produced raspberry-type spherical particles. We confirmed that prepared ZIF-8 particles have BET surface area of ～1500 m²/g and exhibit the gate adsorption behavior caused by the structural transition of the ZIF-8 framework.