A Study of the Mechanism of Micropore Filling. I. Molecular Sieve Effects

Abstract

The adsorptive properties of two microporous carbons and a microporous silica have been investigated and compared using argon and benzene. The micropore volumes determined using the Theory for Volume filling of Micropores (TVFM) agreed to within 40/o of the total micropore volumes determined from the a8 method of pore analysis. Adsorption data of argon at 77 °K and benzene at 298 °K on the microporous carbons were interpreted in terms of the Dubinin-Astakhov and Dubinin-Radushkevich equations, and Weibull and Gaussian distributions of the adsorption free energy with pore volume, respectively. The Weibull distribution was found to apply better than the Gaussian distribution, although variations from linear D-A plots occurred. The adsorption data on the silica sample were best interpreted as a two-term D-R equation. Plots of the distribution of adsorption energy with pore volume of the silica sample for each term of the D-R equation and their effective contribution to the cumulative distribution curve gave conclusive evidence of the ordering of the adsorption process within micropores of varying dimensions

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