From Metal-Organic Framework Powders to Shaped Solids: Recent Developments and Challenges
Résumé
Metal-organic frameworks represent a class of porous materials which developed
considerably over the past few years. Their highly porous structure makes them
outperforming conventional adsorbents in hot topics such as dihydrogen and methane
storage, and carbon dioxide capture. Their consequent modularity, based on the assembly of
organic linkers and metal ions or clusters, also brings novel perspectives in catalysis, sensing
and drug delivery just to name a few. However, one of the main bottlenecks to their broader
use remains their shaping. Especially, shaped materials should present a long-term
mechanical stability as well as preservation of the physical and chemical properties. This
makes shaping of MOFs a special case as their thermal and chemical stabilities remain a
downside as compared to other traditional porous materials such as silicas and zeolites
today. Therefore, an over-increasing effort has been devoted to the shaping of these
materials.
In this review, the state of the art for the preparation of shaped 3D MOF-based materials is
presented. Emphasis will be given to the final physical and chemical properties of the shaped
solids comparatively to the initial powders, when data are available. In the first part,
traditional techniques based on applying a significant force to MOF-based powders will be
reviewed. These include pelletization, granulation, extrusion which generally lead to an
increase of the final volumetric gas uptake of the objects. At the same time, advantages and
disadvantages of each technique will be discussed as well as the main outcome on the final
objects. In the second part, focus will be given on the newly-emerging techniques such as 3D
printing and spray drying. The former also maximizes the volumetric gas uptake of the final
materials and for both techniques the quality of the final objects heavily rely on the working
parameters. Finally, the third part will include the so-called “phase separation” shaping
techniques which are for the most part performed without using special techniques. This
implies shaping via physical and chemical phenomena such as sublimation or precipitation.
Subsequently, a discussion will be proposed on the performance of these materials for
adsorption-based applications. Finally, perspectives and future outlook will be discussed.
Domaines
CatalyseOrigine | Fichiers produits par l'(les) auteur(s) |
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