The diffusion coefficient for xenon in zeolite NaY at infinite dilution was calculated at low temperatures within a hopping model based upon cage-to-cage migration alone. Diffusion was modeled as a sequence of jump events that could consist of several barrier passages. The number of jump events was calculated from transition-state theory by using the potential of mean force as a basis. The potential of mean force was essentially independent of temperature. In the conversion of the jump rate to the diffusion coefficient, dynamic corrections were taken into account. The mean number of barrier passages per jump event increased significantly when the temperature was increased. However, the contribution of the dynamic corrections to the activation energy remained small. In the range of 140 to 210K, the diffusion coefficients obtained from the hopping-model (table 56) were in excellent agreement with the corresponding data arising from conventional molecular dynamics simulations.

Xenon Diffusion in Zeolite NaY:  Transition-State Theory with Dynamical Corrections. T.Mosell, G.Schrimpf, J. Brickmann: Journal of Physical Chemistry, 1996, 100[11], 4582–90

Table 56

Hopping-Model Results for

Xe Diffusivity in NaY Zeolite