BET analysis (after Brunauer, Emmett, and Teller) is a physical method for determining the specific surface area of materials. It is based on the adsorption of gases onto the surface of a solid and is a commonly used technique in materials science, particularly in the characterization of activated carbons, zeolites, or aluminum oxides (Al₂O₃). Due to their porosity and inertness, these materials are suitable as support materials for the dispersion of metal particles in catalysts.
In this process, the amount of an inert gas adsorbed onto the surface of the material via physisorption is measured as a function of pressure, forming a monomolecular layer (1). Nitrogen (N₂) is usually used for this purpose at cryogenic temperatures (approx. -196 °C).
The determined specific surface area makes it possible to detect changes in the structure, such as those that occur during catalyst deactivation through coking, sintering processes, or simply the clogging of a pore by unwanted particles. Furthermore, BET analysis enables the characterization of microporous materials, which are not detected by mercury porosimetry.
