On an isotherm thermodynamically consistent in Henry’s region for describing gas adsorption in microporous materials

Pera-Titus, Marc 2010. On an isotherm thermodynamically consistent in Henry’s region for describing gas adsorption in microporous materials. Journal of Colloid and Interface Science 345 (2) , pp. 410-416. 10.1016/j.jcis.2010.01.027

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Abstract

The Dubinin–Astakhov and Dubinin–Radushkevich isotherms, originally formulated from the classical volume filling theory of micropores, constitute the most accepted models for describing gas adsorption in microporous materials. The most important weakness of these equations relies on the fact that they do not reduce to Henry’s law at low pressures, not providing therefore a proper characterization of adsorbents in the early stage of adsorption. In this paper, we propose a way out of this inherent problem using the thermodynamic isotherm developed in a previous study [J. Llorens, M. Pera-Titus, J. Colloid Interface Sci. 331 (2009) 302]. This isotherm allows the generation of a series of equations that make available a comprehensive description of gas adsorption for the whole set of relative pressures (including Henry’s region), also providing explicit information about energy heterogeneity of the adsorbent through the two characteristic m parameters of the thermodynamic isotherm (i.e., and ). The obtained isotherm converges into the Dubinin–Astakhov isotherm for relative pressures higher than 0.1, the characteristic parameter of this isotherm being expressed as and the affinity coefficient as a sole function of . An expression differing from the Dubinin–Astakhov isotherm has been obtained for describing Henry’s region, providing relevant information about confinement effects when applied to zeolites.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Publisher:	Elsevier
ISSN:	0021-9797
Date of Acceptance:	8 January 2010
Last Modified:	13 Oct 2020 13:45
URI:	https://orca.cardiff.ac.uk/id/eprint/135413

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