Methane dissociation and syngas formation on Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, and Au: A theoretical study
- Hong Kong Baptist Univ., Kowloon (Hong Kong). Dept. of Chemistry
- Xiamen Univ. (China). Dept. of Chemistry
A theoretical study of methane dissociation and syngas formation on a number of transition metals M (M = Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, Au) is presented. The metal surface is simulated by a M{sub 10} cluster model. Reaction energies for the steps involved are determined. The activation energies have been estimated using the analytic BOC-MP formula. The dissociation energy is shown to be an important factor determining the catalytic activity of the metal. The order of the calculated total dissociation energies (CH{sub 4,s} {yields} C{sub s} + 4H{sub s}) is consistent with the order of methane conversions over the metals. In the presence of adsorbed oxygen, oxygen at metal on-top sites promotes methane dehydrogenation; oxygen at hollow sites promotes methane dehydrogenation on Pt, Cu, Ag, and Au, but shows no such effect on the other transition metals. The difference in the H{sub 2} selectivities can be associated with the difference in the stabilities of OH on the metals. For CH{sub x} couplings, the trend in the calculated combination energies is in agreement with experimental observation.
- OSTI ID:
- 684564
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 185; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
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