Aluminium distribution in ZSM-5 revisited: the role of Al-Al interactions

Ruiz-Salvadora, A.R., Grau-Crespo, R. ORCID: https://orcid.org/0000-0001-8845-1719, Gray, A. E. and Lewis, D. W. (2013) Aluminium distribution in ZSM-5 revisited: the role of Al-Al interactions. Journal of Solid State Chemistry, 198. pp. 330-336. ISSN 0022-4596 doi: 10.1016/j.jssc.2012.10.022

Abstract/Summary

We present a theoretical study of the distribution of Al atoms in zeolite ZSM-5 with Si/Al=47, where we focus on the role of Al-Al interactions rather than on the energetics of Al/Si substitutions at individual sites. Using interatomic potential methods, we evaluate the energies of the full set of symmetrically independent configurations of Al siting in a Si94Al2O192 cell. The equilibrium Al distribution is determined by the interplay of two factors: the energetics of the Al/Si substitution at an individual site, which tends to populate particular T sites (e.g. the T14 site), and the Al-Al interaction, which at this Si/Al maximises Al-Al distances in agreement with Dempsey’s rule. However, it is found that the interaction energy changes approximately as the inverse of the square of the distance between the two Al atoms, rather than the inverse of the distance expected if this were merely charge repulsion. Moreover, we find that the anisotropic nature of the framework density plays an important role in determining the magnitude of the interactions, which are not simply dependent on Al-Al distances.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/36086
Item Type	Article
Refereed	Yes
Divisions	No Reading authors. Back catalogue items
Publisher	Elsevier
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