Compression of Capillary Liquid in Porous Alumina

Abstract

Real density ρr (Tables 1 and 2) and sorption property (Table 3) of porous alumina and silica were measured by use of several kinds of liquid. The pore structure of each sample was diversified by calcination at different temperatures. No difference in pr was detected for silicas with different immersing liquids. But for aluminas, unless calcined at higher temperature, a large difference in ρr was observed.
If this difference in pr is due to the compression of the immersing liquid, the decrease in volume by compression, ΔV, can be expressed by ΔVr=1/ρ. -1/ρ, (Table 4); where pHe is the true density measured with helium gas. A linear relationship between 417, and the volume of BET capacity m, viz. the surface area of the solid (Fig.1) demonstrates that the compres- sion of liquid in a capillary takes place on the solid surface.
The total pore volume evaluated from the saturated amount of the sorption using bulk density of liquid was nearly independent of the kind of liquid used (Table 3). The value became more satisfactory when the compression effect was taken into account (Table 5). Present results imply that the compression of the adsorbed layer takes place in the measurement of sorption as well as in the measurement of density.