Structures, energies, and electrostatics for methane coniplexed with alumina clusters

Ellen F. Sawilowsky, Oussania Meroueh, H. Bernhard Schlegel, William L. Hase

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Ab initio calculations were used to investigate properties of complexes formed from the association of CH4 with Al2O3, Al4O6, and Al8O12 alumina clusters. Methane attaches to a surface Al atom of the cluster to form a complex with an Al-C separation that varies between 2.2 and 2.5 Å. The rotational motion for methane in these complexes is highly fluxional. Extrapolated G2MP2 well depths for the CH4- - -Al2O3, CH4- - -Al4O6, and CH4- - -A18O12 complexes are 21, 14, and 17 kcal/mol, respectively. These different well depths are determined by the accessibility of the Al atom to which CH4 binds and the size of the alumina cluster. The electrostatics of the three alumina clusters are very similar, with a charge on the surface Al atom of +2.2 to 2.3. The potential energy surface for a CH4- - -Al2nO3n cluster is represented semiquantitatively by an analytic function consisting of two-body potentials. The results of this study suggest that the adsorption energy for alkane molecules binding to alumina materials depends very strongly on the structure of the binding site.

Original languageEnglish (US)
Pages (from-to)4920-4927
Number of pages8
JournalJournal of Physical Chemistry A
Volume104
Issue number21
StatePublished - Jun 1 2000
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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