Kinetic Monte Carlo simulations were used to model the diffusion of molecules in zeolites. A variety of loading dependences of the Maxwell-Stefan diffusivity, Di, could be realized by allowing the jump frequencies, v, of molecules to be influenced by the presence of neighboring molecules. Neighboring molecules were assumed to reduce or increase the activation energy for diffusion by δE and the jump frequencies v were altered by a factor f = exp[δE/RT] for each neighboring molecule. Using appropriate choices of v and f, the loading dependence of Di could be made to match those obtained from either molecular dynamics simulations or experiment. The major advantage of the kinetic Monte Carlo simulation strategy was that considerably less computer power was required than for the corresponding molecular dynamics simulations. Kinetic Monte Carlo simulations permitted mixture diffusion to be probed without additional parameter tuning. The kinetic Monte Carlo simulations also confirmed the applicability of the quasi-chemical theory of Reed and Ehrlich (1981) for describing the loading dependence of Di.

Kinetic Monte Carlo Simulations of the Loading Dependence of Diffusion in Zeolites. R.Krishna, J.M.van Baten: Chemical Engineering and Technology, 2005, 28[2], 160-7