Activation of Light Alkanes on Pure and Fe and Al Doped Silica Clusters: A Density Functional and ONIOM Study

Authors : Mehmet Ferdi FELLAH, İşık ÖNAL

Pages : 415-426

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :C-H bond activation was studied by use of density functional theory insert ignore into journalissuearticles values(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.
Keywords : C H bond activation, methane, ethane, silica, Fe doping, Al doping, density functional theory, DFT, ONIOM