Metal-organic frameworks are porous materials that are proposed for use in a variety of gas storage and separation, catalytic, nuclear waste recycling and drug-delivery applications. However, they are produced as microcrystalline powders, which collapse when classical shaping techniques such as sintering or pelletization are employed.
This paper shows how controlling the synthesis conditions of a variety of MOFs, e.g. UIO-66 (image below: top left, top middle) avoids the production of powders, and instead results in gels (top right). These gels can then be heated to form mesoporous aerogels or xerogels (bottom left, bottom middle), before being shaped. Furthermore, the gel state can be utilized to enable to the production of microspheres of MOFs (bottom right). Such shaped structures are of much greater promise for industrial application.
B. Bueken, N. Van Velthoven, T. Willhammar, T. Stassin, I. Stassen, D. A. Keen, G. V. Baron, J. F. M. Denayer, R. Ameloot, S. Bals, D. De Vos and T. D. Bennett, "Gel-Based Morphological Design of Zirconium Metal-organic Frameworks", Chem. Sci. (2017).