Temperature Influence of Benzene Adsorption by a Microporous Silica

The theory for volume filling of micropores is used to describe benzene adsorption isotherms measured over a 25 K temperature range. The adsorption potential or molar work of adsorption for the isotherm at 298 K is derived and compared with Weibull, Gaussian, and gamma potential distribution functions. The Weibull function is fitted via a two-term Dubinin-Radushkevich (D-R) equation. The closest data fit occurs for the gamma distribution. The two-term D-R potentials are interpreted as indicating adsorption by primary micropores followed sequentially by secondary micropores. Analysis of the distribution of adsorption enthalpy for the porous solid compared with a nonporous standard suggests that the predominant pore width is 1.2 nm. The interpretation of the differential molar adsorption entropy at 298 K suggests that strongly localized adsorption occurs in the primary micropores and two-dimensional translational motion with rotation in the plane of the ring occurs in the secondary micropores. Copyright 2000 Academic Press.