期刊
APPLIED CATALYSIS B-ENVIRONMENTAL
卷 282, 期 -, 页码 -出版社
ELSEVIER
DOI: 10.1016/j.apcatb.2020.119621
关键词
Perovskites; Three-Way-Catalyst; La-deficient La1-xFeO3; Dual calcium copper substitution; CO and propene oxidation
资金
- EU-Partial-PGMs project [H2020-NMP-686086]
- Chevreul Institute (FR 2638)
- Ministere de l'Enseignement Superieur et de la Recherche
- Region Nord -Pas de Calais
- FEDER
Substituting calcium and copper in A-site and B-site of perovskites respectively led to significant improvements in CO and propene oxidation kinetics. The dual substituted samples were more stable, with calcium substitution stabilizing copper inside the perovskite lattice and slowing down subsequent surface agglomeration, leading to optimal performances in certain compositions. A progressive shift from suprafacial to intrafacial mechanism was observed in stoichiometric perovskites involving the redox Fe4+/Fe3+ couple and lattice oxygen species, resulting in a loss in rate.
Calcium and copper substitutions, in A-site and B-site respectively, of parent stoichiometric LaFeO3 and La-deficient La0.7FeO3 perovskites led to significant improvements in the kinetics of CO and propene oxidation in typical three-way operating conditions. La-deficient La0.7Fe1-yCuyO3 perovskites were found more prone to surface copper oxide segregation leading to more active extra-framework copper oxide species in CO oxidation. Optimal performances were obtained on La0.7Fe0.8Cu0.2O3 composition. At higher Cu content, strong copper agglomeration leads to deactivation. More stable systems were obtained on dual substituted samples thanks to calcium substitution stabilizing copper inside the perovskite lattice and slowing down subsequent surface agglomeration. Rate enhancements in propene oxidation is observed on A-site deficient La0.6CaxFe0.8Cu0.2O3 with x <= 0.2 but a sharp loss in rate is observed on stoichiometric La0.6Ca0.4Fe0.8Cu0.2O3 perovskite explained by a progressive shift from suprafacial to intrafacial mechanism involving in this latter case the redox Fe4+/Fe3+ couple and lattice oxygen species.
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