• The BET (Brunauer-Emmett-Teller) and BJH (Barrett-Joyner-Halenda) methods are commonly used in catalyst characterization. The BET method is primarily used to measure the surface area of a material, while the BJH method is used to analyze the pore size distribution. However, it's important to note that the BJH method also provides surface area values in its results. The difference in surface area values obtained by the BET and BJH methods is due to the different approaches used in each test. The BET method relies on physical adsorption of gas molecules on the surface of the material to calculate the active surface area. On the other hand, the BJH method uses gas adsorption analysis to measure and analyze the pore volume and pore size distribution. The BET method is widely used for measuring surface area in scientific studies because it provides a good estimation of the active surface area and is considered more accurate. It is the recommended method for general surface area measurements. However, it is not suitable for accurately characterizing pores other than mesopores, which are pores with a size range of 2-50 nm. If your focus is on studying small or micropores, such as macropores or micropores, it is advisable to use the BJH method for a more precise analysis of pore size distribution. The BJH method can provide additional information about the distribution and volume of different pore sizes. In summary, the BET method is commonly used for surface area measurements due to its accuracy and widespread use in scientific research. However, in the case of studying small or micropores, the BJH method is recommended for a more comprehensive analysis of pore size distribution.

BET permet de calculer la surface totale dans la plage de 0,05 à 0,35, qui est une plage suffisante pour couvrir la surface totale (une couche de gaz), quelle que soit la nature des pores. La méthode BJH permet d'obtenir d'autres données telles que le diamètre et la volume des pores en plus de la surface horizontale recouverte par plusieurs couches de gaz à une pression de 0,99.