A spray-drying continuous-flow method for simultaneous synthesis and shaping of microspherical high nuclearity MOF beads

Abstract

Metal–organic frameworks (MOFs) are among the most attractive porous materials currently available. However, one of the challenges precluding their industrial exploitation is the lack of methods for their continuous production. In this context, great advances have been enabled by recently discovered, novel continuous-fabrication methods such as mechanosynthesis, electrochemistry, continuous-flow synthesis and spray-drying. Herein we report the benefits of coupling two of these processes—spray-drying and continuous flow—for continuous synthesis of MOFs assembled from high-nuclearity secondary building units (SBUs). Using the resulting spray-drying continuous flow-assisted synthesis, we have prepared numerous members of diverse MOF families, including the UiO-66, Fe–BTC/MIL-100 and [Ni₈(OH)₄(H₂O)₂(L)₆]_n (where L = 1H-pyrazole-4-carboxylic acid) series. Interestingly, all of these MOFs were automatically obtained as compact microspherical superstructures (beads). We anticipate that our strategy could be easily employed for synthesizing and shaping multivariate (MTV) MOFs.