The pore size distribution and pore structure of the original silica gel used for the present surface-treatment experiments were found to be invariant through the determination of argon adsorption isotherm at 77K and the surface area, as long as it was activated at lower temperatures than 450°C. The silica gel was treated with alicyclic alcohols, e. g., cyclopentanol, cyclohexanol, cycloheptanol, cyclohexane methanol and cyclohexane ethanol in an autoclave. The adsorbed amount of argon at 77K on these surface-treated silica gels showed an appreciable decrease in the whole range of relative pressure in comparison with that of the original silica gel and the surface area of these silica gels also decreased. The surface groups of these surface-treated silica gels except the ones treated with cyclohexane methanol or cyclohexane ethanol were driven off from the substrate almost perfectly by pyrolysis of these silica gels at 450°C. The argon adsorption isotherm at 77K and the surface area of these silica gels after pyrolysis at 450°C showed a fairly good agreement with those of the original silica gel.
