VAPOR-LIQUID PHASE-EQUILIBRIUM IN RANDOM MICROPOROUS MATRICES

The theory developed by Madden and Glandt [J. Stat. Phys. 51, 537 (1988)] for fluids in disordered microporous matrices is extended. A perturbation theory approach is used to obtain the free energy of the confined fluid, with the interparticle potential as the perturbation variable. The theory is combined with a mean-field approximation and applied to a system of square-well particles for which vapor-liquid coexistence envelopes are obtained. The effects of matrix density on the coexistence properties are explored, and a comparison is done with previous experiment and lattice modeling.