Surface Resistance to Heat and Mass Transfer in a Silicalite Membrane. A Non-Equilibrium Molecular Dynamics Study

1. Introduction Zeolites are microporous materials which are ideally suited for different industrial applications, e.g. as separators or catalysts. Their applicability is determined by the dynamical and the adsorptive properties of the molecules inside their micropores. Adsorption kinetics in zeolite has been explained as a two-step process, adsorption on the external crystal surface and subsequent inter-crystalline diffusion [1]. Recently much attention has been given to the resistance to transport of molecules at the external surface. It has been attributed to the crossing of potential barriers at the entry of the pores [1] or/and to the probability that a gaseous molecule sticks to the external surface [2]. Moreover, in the early 80's, Ruthven suggested the presence of additional heat resistances at the external surfaces that slow down the kinetics of the exothermic adsorption processes [3]. Here, using non-equilibrium molecular dynamics simulations (NEMD), we give evidences for the presence of mass and heat resistances at the external surface of a silicalite-1 membrane when n-butane is adsorbed [4].