ON THE DIFFUSION MECHANISM OF METHANE IN A CATION-FREE ZEOLITE OF TYPE ZK4

Molecular dynamics (MD) simulations were performed in order to examine the mechanism of diffusion of guest molecules in a cation-free zeolite of type ZK4. The peculiarities of molecular motion are illustrated by the probability distribution of the residence times in the large cavities and by the velocity autocorrelation functions in combination with trajectory studies. Depending on the potential parameters used the diffusivities may increase or decrease with increasing concentration. The diffusion coefficients are found to follow an Arrhenius law which is examined for different loadings.