| Abstract
| - Molecular dynamics simulations were performed in order to obtain a detailed understanding of the self-diffusion mechanisms of methanol in the zeolite NaY system. We derived a new force-field term to describethe interactions between the methanol molecules and the extraframework cations. From the simulations, weshow that diffusive behavior in the high-temperature range consists of a combination of both short- andlong-range motions at low and intermediate loadings. This type of motion is characterized by an activationenergy that decreases as the loading increases. At low loadings, we also observe short-range diffusive behaviorbased on a surface-mediated mechanism. The short-range behavior corresponds to motion only on the lengthscale of an FAU supercage, whereas the long-range behavior involves intercage diffusion. For the saturationloading corresponding to 96 methanol molecules per unit cell, only short-range motions within the samesupercage predominate. Finally, the preferential arrangement of the adsorbate molecules around theextraframework cations are examined and compared with those previously deduced from experimental data.
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