抄録
The pore structure of silica gels surface-treated with phenyl trichlorosilane, pheneylmethyldichlorosilane, diphenylmethylchlorosilane and trimethylchlorosilane, was investigated through 77°K Ar adsorption isotherms over these silica gels treated thermally at 130°, 250°, 350° and 450°C, respectively. The relationship of the apparent surface area B′σ to the micropore volume N0 and the surface area Bσ of the plane surface in macropores and the relationship of the apparent BET constant C′ against the micropore volume N0, were determined through the use of the B′ and C′-value obtained by applying the composite adsorption isotherm composed of the isotherm for the micropore, and that for the macropore, to the BET equation. The values of B and N0 obtained by applying the BET apparent surface area B′σ and apparent BET constant C′ for Ar adsorption isotherms over surface-treated silica gels to these relationships agreed with those obtained by the αs-plot for the respective isotherms. Accordingly, these Ar adsorption isotherms were ascertained to be composite isotherms. It is possible to detect these Ar isotherms by the αs-plot method. Although the numbers of surface groups were unchanged by heating these surface-treated silica gels at 130°, 250°, 350° and 450°C, the adsorbed amount on each sample increaed throughont the whole pressure range, increasing the temperaure of thermal treatment. The surface area of the plane surface for the macropore was unchanged, while the micropore volume increased. The volume of the micropore increased in proportion to the amount of dehydration due to thermal treatment.
