Low temperature intracage and intercage migration rates for guest atoms of varying sizes in zeolite NaY

Abstract

A recently proposed method has been employed for the calculation of the rate of intracage and intercage migration of Lennard-Jones (LJ) particles in NaY zeolite at low temperatures and over the linear and anomalous regimes in the D vs. 1/ σ 2 plot by varying σ, the LJ diameter. It is seen that for particles in the linear regime over the temperature range 10–100 K, the intra and intercage rates vary over 26–32 orders of magnitude. In comparison, for particles in the anomalous regime, the variation is just over 14 orders of magnitude. Activation energies obtained are consistent with earlier reports. The rate determining step is always the intracage site-to-site hop and not intercage hop as one would have expected.