３パラメーター吸着式の誘導とその適応性 （第６報） 無孔性ＴｉＯ２，Ａｌ２Ｏ３粉体へのＮ２等温線の３パラメーター吸着式への適応性

Abstract

The application of the 3-parametric adsorption equation to N2-adsorption isotherms on non-porous powders, two kinds of TiO2 and Al2O3 which were confirmed to be a non-existent micropore due to αs-plots was investigated in comparison with the adaptability of the BET equation to these isotherms and by the comparison of the surface areas due to respective adsorption equation, outerplane surface areas due to αs-plots, surface areas using the SEM method and the flow method with those due to the adsorption method. The surface areas due to each adsorption equation agreed with each other within 20%, irrespective of its derivation on different bases. The outerplane surface areas and surface areas due to the SEM and flow methods agreed with those from the adsorption method within 20% too. Thus, it is undecided which is a reasonable adsorption equation to obtain the reasonable surface areas. However, the BET equation agreed with the experimental adsorption isotherms in the range of relative pressure from 0.05 to 0.3 at which the monolayer was completed and in the upper range of the relative pressure of 0.3, the equation predicts a steep increase in the amount adsorbed more than that of the experimental isotherms. The 3-parametric adsorption equation agreed with experimental ones in a wider range of from 0.05 to 0.6 or 0.7 more than that of the BET equation. Since the latter equation showed an agreement in the relative pressure range higher than 0.3 in which the monolayer was completed, the upper adphase over the monolayer was conceived to be formed not by a stacked layer as in the BET model but rather by the mobile adphase on the basis of a 3-parametric adsorption equation.