Water-Hydrophobic Zeolite Systems

Water intrusion-extrusion in hydrophobic microporous AFI, IFR, MTW and TON pure silica zeolites (zeosils) has been investigated through molecular dynamics (MD) simulations. It was found that intruded water volumes correlate with the free volume of the zeosil unit cells. Calculated adsorption isotherms allowed us to estimate the amounts of water intruded, and deviations from experiments (lower experimental with respect to calculated intrusion pressures) have been;explained in terms of connectivity defects in the synthesized materials. Water phase transitions in defectless zeosils occur in a narrow range at high pressure. On the basis of a simple model, we derived a thermodynamic equation tha…