In-situ construction of hierarchically porous MOF monoliths using high internal phase emulsion templates

The construction of MOF monoliths can solve the drawbacks of MOF powders in practical applications that can cause high pressure drop, low mass transfer efficiency, clogging, and complicated operation and recycling treatment, but there are still problems such as MOF pore clogging, difficulty in tuning the pore structure of the monoliths, and poor mechanical properties. Herein, nearly pure ZIF-8 monoliths with hierarchical pore structure were prepared by in-situ converting the amorphous ZIF-8/ZnO nanoparticles stabilized HIPE templates into continuous ZIF-8 skeleton. The obtained ZIF-8 monoliths exhibit low bulk densities of ∼ 80 mg cm−3, high BET surface areas of up to 961.3 m2/g, and good mechanical properties. The monolith maintained high catalytic activity for 30 h in the Knoevenagel reaction using a homemade continuous flow reactor, revealing its high efficiency and good stability. This work provides a worth-adopted approach to prepare MOF-based monoliths for applications such as adsorption, separation, catalysis and effluent treatment.