Abstract
AbstractSurface area determination with the Brunauer–Emmett–Teller (BET) method is a widely used characterization technique for metal–organic frameworks (MOFs). Since these materials are highly porous, the use of the BET theory can be problematic. Several researchers have evaluated the BET method to gain insights into the usefulness of the obtained results and interestingly, their findings are not always consistent. In this review, the suitability of the BET method is discussed for MOFs that have a diverse range of pore widths below the diameters of N2 or Ar and above 20 Å. In addition, the surface area of MOFs that are obtained by implementing different approaches, such as grand canonical Monte Carlo simulations, calculations from the crystal structures or based on experimental N2, Ar, or CO2 adsorption isotherms, are compared and evaluated. Inconsistencies in the state‐of‐the‐art are also noted. Based on the current literature, an overview is provided of how the BET method can give useful estimations of the surface areas for the majority of MOFs, but there are some crucial and specific exceptions which are highlighted in this review.
Highlights
Surface area determination with the Brunauer–Emmett–Teller (BET) method is a widely used characterization technique for metal–organic frameworks (MOFs)
To examine the applicability of using CO2 isotherms at 273 K to obtain the BET surface areas of MOFs in a similar way that it was performed for N2 and Ar isotherms, Kim et al.[51] selected different types of porous materials and classified them based on their pore sizes into four groups
This review has summarized work that has been performed involving the applicability of the BET method for determining surface areas of MOFs
Summary
The fundamental element of BET theory is associated with the adsorption of a gas on the material’s surface.[61,62,63] This phenomenon is caused by van der Waals forces that are created by a film of the adsorbate, which consists of atoms, ions, or molecules on the surface of a substance that adsorbs these particles. The pores of molecular dimensions.[85] When characterizing materials with micropores below 20 Å, the biggest problem is usually related to micropore filling, which takes used.[74,80,81] since the linearity is not always restricted place rather than mono or multilayer coverage This can lead to to this range, Rouquerol et al.[82,83] recommended four consist- obtaining higher or overestimated surface areas; high ency criteria as follows: rates of micropore filling can potentially be recognized.[85,86,87,88,89]. Where L is the Avogadro constant and m is the mass of adsorbent
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