On the Scale-Up of Metal-Organic Frameworks using Microreaction Technology: The cases of ZIF-8 and UiO-66

In this work ZIF-8 and UiO-66 were synthesized continuously by employing microreactors and the concept of flow chemistry. The microreaction technology (MRT) process turned out to be a viable alternative to the time and energy consuming conventional synthesis processes, as significantly faster reaction rates could be achieved compared to the conventional batch processes. The two cases differed significantly concerning the results. In particular, for ZIF-8 it has been demonstrated that the implementation of microreaction technology is a powerful technique to significantly enhance productivity and repeatability. ZIF-8 was obtained at production rates of >1 kg/day and a theoretical space-time yield of 400,000 kg/m3*day while the production costs have been reduced to <1 €/g and the modular process setup allows easy further scale-up. Conversely, the results of the process intensification in the case of UiO-66 revealed a different behavior. A correlation between intensified conditions and high product quality has been established. Escalation of the reaction conditions above a certain threshold leads to poor formation of the material and inferior product properties.