Phase diagrams of simple fluids in porous globular adsorbents

A globular model for silica-gel systems has been proposed in order to perform calculations for adsorption in porous systems on basis of the lattice–gas model. The globular model operates with fixed size spherical particles. These particles form a nonregular structure, which can be constructed by removing of a portion of globules from the regular three-dimensional cubic structure. Types of phase diagrams for the vapour–liquid transition of an adsorbate in porous globular adsorbents with regular and nonregular structures have been considered. The calculations for three types of adsorbates: nitrogen, argon and a model system with low binding energy of an adsorbent were performed. A size of globules was changed from 7 up to 40 lattice parameter of the model. The phase diagrams of the model have several domes which correspond to surface, over-surface, and inner part of pore volumes.