Metal-organic frameworks (MOFs) are porous materials that have a range of industrially relevant applications including gas storage and catalysis. For more information on MOFs, read our feature article on porous frameworks.
Zeolitic imidazolate frameworks (ZIFs) are a sub-class of MOFs that are comprised of metal ions linked by imidazole derivatives, such as ZIF-8, which is a framework built up of zinc metal and 2-methylimidazole ligands.
Although ZIF-8 could have widespread applications in industry, its synthesis requires large quantities of methanol, even at a small scale. In this study, published in Nature Communications Chemistry, researchers from the chemicals company Johnson Matthey investigated the feasibility of making ZIF-8 by first making a different MOF, ZIF-L, and then transforming it. This method would use much lower volumes of water and organic solvent, making it better for the environment, and they wanted to know if it would be economically viable and scalable to industrial quantities.
To discover whether this synthesis route would work, the researchers investigated the transformation of ZIF-L to ZIF-8 in detail using a range of techniques, including inelastic neutron scattering (INS) on Tosca.
Their results showed that their method was successful, and they were also able to understand more about the mechanism of the transformation. Indeed, the insight gained from using INS proved the value of using spectroscopy for investigating the progress of the reaction, indicating that other forms of spectroscopy could be used in situ to determine when the transformation is complete.
On scaling up their method, they were able to successfully produce one kilogram of ZIF-8. This pilot formed the basis of an economic analysis of the estimated costs of production and corresponding yields, showing that this method could produce over six times more ZIF-8 than direct methods.
By using neutron spectroscopy at ISIS, this industrial collaboration was able to understand the chemistry of their production process in more detail. This aids them in their development of larger-scale processes that produce more material at a lower cost, whilst also reducing environmental and safety concerns.
The full paper can be found online at DOI: 10.1038/s42004-021-00613-z