Adsorption and pore condensation of krypton on mesoporous silicas at 77 K

The adsorption and pore condensation behavior of krypton was studied on the series of well-defined mesoporous silicas (mode pore diameter 2.6–6.0 nm) and one sample of disordered mesoporous silica (mode pore diameter 7.5 nm) at 77 K. The similar adsorption measurement was carried out on non-porous silica Davisil. The results show clearly that the pore condensation of krypton occurs only in mesopores whose diameter does not exceed 6 nm. The krypton pore condensation vanishes in larger mesopores, which limits information obtainable from the isotherm. This phenomenon can be explained on the basis of Broekhoff and de Boer thermodynamic theory of capillary condensation.