Andreas Schuring, Scott M. Auerbach,
Siegfried Fritzsche and Reinhold Haberlandt,
"Random Walk Treatment of Dumb-Bell Molecules in an LTA Zeolite
and in Chabazite,"
Stud. Surf. Sci. Catal. 154, 2110-2117 (2004).
Abstract
We analyse the mechanisms of self diffusion in zeolite-guest systems
which show a non-monotonic temperature dependence of the self diffusion
coefficient D: ethane in a cation-free LTA zeolite and chlorine in
silicious chabazite. In these systems, D is influenced by jump
rates for crossing energetic barriers as well as for crossing entropic
barriers. The latter decrease with increasing temperature.
Employing random walk descriptions, simple analytical formulas are
derived that relate the self diffusion coefficient of the guest
molecules with the jump rates for crossing the different barriers.
The simple ansatz we use can be transfered to other zeolite-guest systems.
Prof SM Auerbach
12 May 2005