Molecular dynamics simulations of n-butane and n-hexane diffusion in silicalite

Abstract

We report molecular dynamics simulations of n-butane and n-hexane adsorbed in the zeolite silicalite. These systems have been modelled within a rigid framework approximation and a Ryckaert-Bellemans model was adopted to describe the adsorbed molecules. The parametrization due to June, Bell and Theodorou has been used to describe the host-guest molecule interactions. Long simulations (1000 ps) have been performed, modelling these systems at a variety of sorbate loadings and temperatures. These have allowed us to investigate how the presence of the zeolite framework affects the thermodynamic properties, confomational distributions and diffusion related properties of the adsorbed molecules, and their response to changes in the loading and temperature. We have obtained estimates of the diffusion coefficients and activation energies which are in good agreement with experimentally measured data.