Adsorption Deformation in Multicomponent Porous Systems

A generalization of the procedure for calculating the local mechanical moduli of multicomponent porous materials in the process of adsorption deformation by a mixture of adsorbed molecules is discussed. The porous system is modeled by a two-level structural model consisting of interconnected systems of globules/grains and a system of pores inside which adsorption occurs. The adsorbate simultaneously affects the outer and inner surface of the adsorbent, changing the volume of the sample with a fixed amount of adsorbent. Based on two-level structural models of deformable porous bodies within the framework of the lattice gas model, equations are formulated that provide a self-consistent description of the change in their volume and partial adsorption isotherms as a function of the external pressure of the adsorbate at a fixed temperature. For simplicity of presentation of the calculation scheme, commensurability of the sizes of the atoms of the solid body and the components of the mobile phase of the adsorbate is assumed. The molecular level reflects the intrinsic volume of molecules and their lateral interaction in the quasi-dimeric approximation. The supramolecular level of the model is represented as a grain of a porous material with a given distribution function of interconnected pores of various types and sizes. Using the compression modulus as an example, a method for calculating average local mechanical moduli characterizing the mechanical properties of solids is considered.