Activation of light alkanes on pure and Fe and Al doped silica clusters: A density functional and ONIOM study

Fellah M. F., ÖNAL I.

TURKISH JOURNAL OF CHEMISTRY, vol.31, no.5, pp.415-426, 2007 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 31 Issue: 5
  • Publication Date: 2007
  • Journal Name: TURKISH JOURNAL OF CHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, TR DİZİN (ULAKBİM)
  • Page Numbers: pp.415-426
  • Middle East Technical University Affiliated: Yes

Abstract

C-H bond activation was studied by use of density functional theory (DFT) and ONIOM calculations as implemented in Gaussian 2003 at the B3LYP level utilising 6-31G* as the basis set for Si, Al, and Fe atoms and 3-21G** as the basis set for O and H atoms. Relative energy profiles were determined for pure silica modeled by a Si7O21 cluster and Fe and Al doped silica clusters via coordinate driving calculations. The activation barriers for C-H bond activation of methane and ethane decrease with the substitution of Fe on the silica surface, which theoretically demonstrates a favorable effect of Fe substitution on that surface. The activation energy barriers of methane and ethane are substantially decreased from the approximate transition state values of 55.14 kcal/mol and 54.89 kcal/mol for pure silica cluster to 33.43 kcal/mol and 36.54 kcal/mol obtained for the approximate transition state for Fe substituted silica, respectively.