SORBATE-LOADING DEPENDENCE OF DIFFUSION MECHANISM IN A CUBIC SYMMETRYZEOLITE OF TYPE ZK4 - A MOLECULAR-DYNAMICS STUDY

In the present work we investigated how the sorbate loading controls t he diffusion of spherically symmetric Lennard-Jones molecules in a cat ion-free zeolite of type LTA. This effect is studied by taking into ac count the mechanical flexibility of the framework, which allows for th e energy relaxation of the sorbed molecules along with fluctuations of the window diameters. The number density of the adsorbed molecules wa s increased from 1 up to 15 methane molecules per cavity, which means from 8 up to 120 particles adsorbed in one unit cell. We have shown th at the sorbate loading strongly alters the diffusion mechanism by indu cing a transition at seven molecules per cavity from an increasing to a decreasing mobility regime.