Adsorption-Induced Deformation of Microporous Carbons: Pore Size Distribution Effect

Abstract

We present a thermodynamic model of adsorption-induced deformation of microporous carbons. The model represents the carbon structure as a macroscopically isotropic disordered three-dimensional medium composed of stacks of slit-shaped pores of different sizes embedded in an incompressible amorphous matrix. Adsorption stress in pores is calculated by means of Monte Carlo simulations. The proposed model reproduces qualitatively the experimental nonmonotonic dilatometric deformation curve for argon adsorption on carbide-derived activated carbon at 243 K and pressure up to 1.2 MPa. The elastic deformation (contraction at low pressures and swelling at higher pressures) results from the adsorption stress that depends strongly on the pore size. The pore size distribution determines the shape of the deformation curve, whereas the bulk modulus controls the extent of the sample deformation.

Adsorption-induced deformation of nanoporous materials—A review

“…While a homogeneous model 108 could work for highly disordered materials, it cannot describe materials where the micropores and mesopores are distributed in a certain well-defined fashion (e.g., SBA-15, in which the mesopores are believed to have a microporous corona around them).…”

“…Despite the number of strong assumptions, this "thermodynamic approach" made it possible to calculate strain isotherms for various other microporous systems, e.g., activated carbons, 108 synthetic carbon monoliths, 50 coal, 95,109 and even breathing MOFs. 101 The key part is that the grand potential of the system (and therefore its derivative) is calculated based on a theory of adsorption in a rigid pore.…”

“…For example, the strains in Ref. 108 are calculated based on grand canonical Monte Carlo (GCMC), and the strains in Ref. 101 are derived analytically based on the Langmuir theory of adsorption.…”

Adsorption and strain: The CO2-induced swelling of coal

“…It is however needed in order to properly describe the CO 2 -induced swelling of coal, which is due to the adsorption of fluid at the interface between solid matrix and pore space (Bangham and Maggs, 1944;Harpalani and Schraufnagel, 1990;Yates, 1954). How adsorption leads to strain has been studied by several, but the results remain mostly based on specific microstructures (e.g., Scherer (1986) or Kowalczyk et al (2008)) and/or on specific sorption strain models (e.g., Pan and Connell (2007) or Palmer and Mansoori (1998) for coal and its implication on permeability changes). The work presented herein aims at proposing a more general framework through which to compute strains caused by adsorption.…”

Adsorption of Gases in Nanomaterials: Theory and Simulations

“…For example, the quasi-1D 3 He system in a very small, rigid carbon nanotube (NT) is found in the gaseous state, while in a non-rigid NT forms a liquid state. Moreover, several authors have addressed the non-rigidity of the substrate in simulations of adsorption, mostly in slit pores, carbons, and zeolites [10][11][12][13][14]. This flexibility is a characteristic that distinguishes MOFs from other materials.…”