(323b) Deformation of Nanoporous Materials in the Process of Binary Adsorption: Methane Displacement By Carbon Dioxide from Microporous Carbons.

Phenomenon of adsorption deformation of nanoporous materials has recently attracted a lot of attention in adsorption and materials science communities. Various theoretical and molecular simulations approaches have been suggested to predict the stress and strain induced by single component adsorption. However, most practical applications, like adsorption separations or selective gas storage, involve multicomponent competitive adsorption. Here, we develop a thermodynamic method based on the notion of the adsorption stress to predict the deformation effects upon binary adsorption. As a practically important example, the process of displacement of methane by carbon dioxide from microporous carbons is considered. This process is the foundation of the secondary hydrocarbon recovery from shales and coalbeds associated with carbon dioxide sequestration.

A general equation is derived to relate the adsorption stress and the adsorption isotherm of multicomponent mixture. Further this theory is adapted for phenomenological models employed for multicomponent adsorption of microporous carbons, such as Langmuir, Dubinin, and IAST. The results are compared with available literature data and Monte Carlo simulations on model structures.

The proposed approach may have multifaceted applications in modeling behavior of hydrocarbon mixtures in micropores of geosorbents, gas separations and carbon capture on flexible adsorbents.