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 zeolit e of type ZK4. The peculiarities of molecular motion are illustrated b y the probability distribution of the residence times in the large cav ities and by the velocity autocorrelation functions in combination wit h trajectory studies. Depending on the potential parameters used the d iffusivities may increase or decrease with increasing concentration. T he diffusion coefficients are found to follow an Arrhenius law which i s examined for different loadings.