Dynamics of alkane mixtures in silicalite pores

The transport of n-butane - methane mixtures in silicalite has been studied at 200 K using molecular dynamics simulations and quasi-elastic neutron sc attering experiments. The dependence on the wave vector of the half-width a t half-maximum of the incoherent dynamic structure factor is indicative of a jump diffusion process. Distributions of the jump lengths of methane usin g a coarse-grained jump model have shown that the jump lengths are widely d istributed between 0 and 15 Angstrom, the mean jump length being a decreasi ng function of the loading. Self-diffusivity values calculated from the dyn amics simulations are in excellent agreement with the experimental measurem ents from quasi-elastic neutron scattering.