The surface-treatment of silica gels was performed as follows : silica gels were surface-treated with phenyl-triethoxysilane and octadecyl-triethoxysilane, then SiO
2 was deposited on silica gel due to pyrolysis of surface-silanized silica gel in an oxygen atmosphere at 510°C. After these silica gels were boiled with water and dried, the same treatments were repeated. The amount of SiO
2 on silica gel was found to be controllable by repeat of these surface-treatment. The pore structure of these silica gels was investigated from the α
s-plots and BET surface areas obtained from Ar adsorption isotherms at 77°K on the silica gels treated with organo-triethoxysilane, silica gels after pyrolysis of these silanized silica gels in an oxygen atmosphere and the silica gels after surface-treatment of oxidized silica gels with boiling water and dryness.
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