Scalable Continuous Flow Metal–Organic Framework (MOF) Synthesis Using Supercritical CO2

The high surface areas and tunable porous structures of Metal–Organic Framework (MOF) materials offer desirable capabilities in a wide range of applications. One challenge to the widespread use of MOFs is a lack of large-scale manufacturing synthesis processes. This paper presents a novel method of continuous synthesis of MOF using supercritical carbon dioxide (scCO2), introduced through a custom counter-current mixer, to provide enhanced heat and mass transfer to MOF precursor materials. The method was used to synthesize the zirconium-based MOF UiO-66 at a production rate of 104 g/h. Synthesis of UiO-66 was confirmed via SEM images, powder X-ray diffraction (PXRD) spectra, and physisorption analysis. Additionally, testing showed that this method could be used to activate as well as continuously synthesize MOF materials. Our method results in rapid reaction time (<3s), can be easily scaled, and it allows for recovery of effluent and unreacted material, which is challenging in hydrothermal and supercritical water-based systems.