On the Mechanism for Hysteresis of Gas Adsorption on Mesoporous Substrates

Abstract

The results of recent measurements of gas adsorption on a series of porous glass substrates with very narrow distributions of pore radii are analysed on the basis of a density functional theory of capillary condensation of a confined fluid. Assuming that hysteresis of the isotherms is associated with metastability of the gaslike configuration in a single pore, the calculated adsorption isotherms are in good agreement with experiment for the series of glasses. Our analysis indicates that for porous substrates of this type the collective effects of the pore network are less important for hysteresis than metastability in individual pores.