Deformation of zeolite CaA granule during krypton adsorption

Adsorption-induced deformation of nanoporous materials—A review

“…12,44,45 These measurements showed strain isotherms similar to carbonaceous microporous adsorbents: an initial moderate contraction at low gas pressure, followed by a noticeable expansion, see Figure 5. Reported strains were of the order of 10 À4 .…”

Adsorption-induced dimensional changes of solids

“…The method of this calculation will now be illustrated on the system zeolite CaA-krypton, which was studied experimentally 10 at the four temperatures 153, 180, 188, and 198 K. Let us consider a point 1 (a ¼ 3.3196 mol kg À1 and ln 2p 1 ¼ 5.82129) on the adsorption isotherm at 198 K shown in Fig. 3 where the relative strain x ¼ 0, as indicated in Fig.…”

“…Considering that x is very small, in eqn. (10) we can neglect the quadratic term x 2 , and finally we obtain…”

“…The first explanation for this phenomenon was also offered by Bangham and Razouk, 7 who assumed that strain within the adsorbent was caused by a variation of spreading pressure, with strain and spreading pressure being proportional to each other. However, this assumption cannot explain the contraction of an adsorbent, which is often observed experimentally, [8][9][10] and it should also be noted that although spreading pressure is one of the reasons for induced strain in porous materials, it is not the main reason. Also, only if adsorption takes place on a nonporous solid up to a moderate equilibrium pressure, does the decrease in interfacial tension upon adsorption cause swelling of the solid.…”

Deformation of Microporous Carbons during N2, Ar, and CO2 Adsorption: Insight from the Density Functional Theory

“…21−32 The extent of observed contraction and expansion depends on the structure of the adsorbent, 27,30 the adsorptive applied, 23,24,31,33−36 and the temperature. 2,28,32,37 The first model for adsorptioninduced deformation of microporous materials was proposed by Bangham, who considered the energy change of the adsorbate−adsorbent interface to be the sole source of stress within the porous structure. 38 This concept was later implemented into the framework of Biot's poromechanics by the use of the Gibbs adsorption equation.…”