The effect of oxygen-anion conductivity of metal-oxide doped lanthanum oxide catalysts on hydrocarbon selectivity in the oxidative coupling of methane
- Ruhr-Universitaet Bochum (Germany)
La{sub 2}O{sub 3} was doped with cations of valencies different to La{sup 3+} (Sr{sup 2+}, Zn{sup 2+}, Ti{sup 4+}, Nb{sup 5+}) to alter the concentration of oxygen-anion vacancies in the host lattice and, hence, oxygen-anion conductivity. The conductivity and catalytic properties of these solids were determined between 700 and 850{degrees}C. An increase in oxygen-anion conductivity improved C{sub 2+} selectivity. A high concentration of anion vacancies in the catalytic material favours the adsorption of gaseous oxygen and its immediate transformation into lattice oxygen: therefrom it is suggested, that the relative amount of weakly adsorbed electrophilic oxygen species (possibly O{sub 2}{sup -}, O{sub 2}{sup 2-}) is diminished in favour of more strongly bounded, nucleophilic species (O{sup 2-}). Thereby, nonselective surface reactions of methyl radicals and/or C{sub 2+} hydrocarbons with electrophilic oxygen are suppressed. 34 refs., 7 figs., 4 tabs.
- OSTI ID:
- 539457
- Journal Information:
- Journal of Catalysis, Vol. 168, Issue 2; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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