Catalysis science & technology, 2015-06, Vol.5 (7), p.3585-3597
2015
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- Autor(en) / Beteiligte
- Titel
- Role of lattice oxygen in oxidative steam reforming of toluene as a tar model compound over Ni/La sub(0.8)Sr sub(0.2)AlO sub(3) catalyst
- Ist Teil von
- Catalysis science & technology, 2015-06, Vol.5 (7), p.3585-3597
- Erscheinungsjahr
- 2015
- Quelle
- Alma/SFX Local Collection
- Beschreibungen/Notizen
- Catalytic steam reforming of tar with toluene as a model compound for production of synthesis gas (H sub(2) and CO) was studied using Ni/LaAlO sub(3), Ni/La sub(0.8)Sr sub(0.2)AlO sub(3), Ni/La sub(2)O sub(3), and Ni/ alpha -Al sub(2)O sub(3) catalysts prepared using a wet impregnation method. The Ni/La sub(0.8)Sr sub(0.2)AlO sub(3) catalyst demonstrated the most superior catalytic performance in terms of both catalytic activity and coke resistance in the steam reforming of toluene. The presence of gas phase oxygen enhanced the catalytic performance of all four catalysts, with the extent of improvement being the greatest over the Ni/La sub(0.8)Sr sub(0.2)AlO sub(3) catalyst. Catalyst characterization by X-ray diffraction (XRD), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption of oxygen (TPD-O sub(2)) revealed that the superior catalytic performance of the Ni/La sub(0.8)Sr sub(0.2)AlO sub(3) catalyst was a result of lattice distortion caused by strontium doping, which produced a higher concentration of oxygen vacancies on the catalyst surface. This lowered the activation energy of the migration of lattice oxygen, enhancing the mobility of lattice oxygen species, and also improved the adsorption abilities of gas phase oxygen species. Mobile lattice oxygen species (O sub(lattice)) favored the direct partial oxidation of toluene, whereas gas-phase oxygen possessed stronger oxidative abilities and favored the complete oxidation of toluene. Both mobile lattice oxygen and gas phase oxygen species actively suppressed coke formation and oxidized coke deposited on the catalyst surface, conferring coking resistance.