Is the bet equation applicable to microporous adsorbents?

This chapter focuses on how the BET equation is applicable to microporous adsorbents. The BET method can be considered, essentially, as a mathematical means to analyze the adsorption isotherm to derive a “monolayer capacity” and then a surface area. The BET method should not be applied to adsorbents containing micropores in every case. Beyond the “linearity criterion” of the BET plot, two other criteria are found necessary, especially in the presence of micropores, to draw the specific advantage of the BET equation. Calorimetric data for adsorption on microporous adsorbents confirm the fact that the BET monolayer content mostly corresponds to the adsorbate in energetical interaction with the surface. For adsorbents containing micropores, the concept of “BET monolayer content” is misleading and could well be replaced by that of “BET strong retention capacity.” This concept includes the adsorbate present in the micropores together with the content of the statistical monolayer on the non-microporous portion of the surface.