Abstract
We have developed a parallel code for Molecular Dynamics (MD) simulations for a system of molecules in zeolite pores with vibrating framework atoms and carried out simulations for diffusion of benzene and three xylene isomers in a mordenite crystallite. It is found that the self-diffusivities of benzene in the flexible framework are three times or more as high as those in the rigid framework, according to the temperature. As for the self-diffusivities of benzene and xylene isomers in the flexible mordenite crystallite, the order in their magnitude is found to be as p-xylene > benzene > m-xylene > o-xylene, which indicates that the diffusivity is influenced by the molecular geometry as well as the dynamic diameter of each molecule. It is noted that molecular orientations of benzene and p-xylene in large pores, which has slightly elliptic shape, are quite different; that is, the molecular planes of benzene are oriented in parallel to the minor axis of the pores while the molecular planes of p-xylene are parallel to the major axis.
