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Modeling benzene orientational randomization in NaY zeolite at finite loadings with kinetic Monte Carlo and master equation methods
 

Summary: Modeling benzene orientational randomization in NaY zeolite at finite
loadings with kinetic Monte Carlo and master equation methods
Cristian Blanco, Chandra Saravanan,a)
and Melissa Allen
Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003
Scott M. Auerbachb)
Department of Chemistry and Department of Chemical Engineering, University of Massachusetts, Amherst,
Massachusetts 01003
Received 30 June 2000; accepted 6 September 2000
We have modeled the orientational dynamics of benzene in NaY zeolite, motivated by the NMR
study of Isfort et al. at loadings of five benzenes per cage Chem. Phys. Lett. 288, 71 1998 . We
consider guest-guest interactions in two stages: first, we include only site blocking; next, we
consider both site blocking and nearest-neighbor attractions. We calculated orientational correlation
functions using kinetic Monte Carlo and also with a mean field master equation MFME . Both
methods produce correlation functions exhibiting biexponential decay in time. Analytically solving
the MFME shows that long-time decay is controlled by a composite of intracage and cage-to-cage
jumps. The apparent activation energy is greater than the fundamental cage-to-cage barrier when
considering only site blocking, but is less than the same fundamental barrier when also including
guest-guest attractions. This suggests that the actual cage-to-cage barrier is greater than the 40 kJ
mol 1

  

Source: Auerbach, Scott M. - Department of Chemistry, University of Massachusetts at Amherst

 

Collections: Chemistry