Adsorption-Induced Deformation of Adsorbents

Abstract

Adsorption-induced deformation of AR-V and AUK carbon adsorbents and NaX zeolite has been studied upon adsorption of n-С₅Н₁₂, n-С₆Н₁₈, n-С₇Н₁₆, and CO₂ at temperatures of 193−423 K. It has been shown that adsorption-induced deformation is positive upon the physical adsorption of gases and vapors on the surface of a nonporous (macroporous) solid when the excess adsorption is positive. When calculating the adsorption-induced deformation in the region of the capillary-condensation filling of mesopores, the additional pressure in capillaries, which is negative (contraction of an adsorbent), must be taken into account in the case of wetting a solid surface with a liquid adsorbate. The compressibility of AUK microporous carbon adsorbent as a porous solid is almost independent of the temperature and the properties of an adsorbate, and, for adsorption of n-C₅H₁₀ and n-C₇H₁₆ hydrocarbons and CO₂, it is γ_а = (5.6 ± 0.6) × 10⁻⁶ bar⁻¹. The compressibility of AUK adsorbent appears to be 87% higher than that of nonporous graphite.