The BJH method utilizes the principles of gas adsorption and desorption. A porous catalyst sample is exposed to nitrogen gas, and the amount of gas adsorbed and desorbed is measured at various relative pressures. The data obtained is then used to calculate the pore size distribution using the Kelvin equation and the thickness of the adsorbed layer. The BJH method assumes cylindrical pores and applies the concept of capillary condensation to evaluate pore sizes.
