RESUMO
A series of oxygen-deficient perovskite-supported palladium catalysts were prepared by the "solid phase crystallization" (spc) method and investigated with XRD, TPR, TPD, TEM, XPS, BET analysis and CO oxidation. It was found that Pd/perovskite catalysts synthesized by the spc method were more active for CO oxidation than the calcined LaCo0.95 Pd0.05 O3, where Pd dispersed in the solid solution. H2-reducing treatment in the spc method could yield not only high-dispersed fine Pd particles on the perovskite surface but also oxygen-deficient structure. In these perovskite-supported Pd catalysts, oxygen vacancies adsorbed, activated and supplied oxygen to the active Pd sites, where the oxidation occurred with adsorbed CO. The high activities were due to the cooperative action of Pd and oxygen vacancies.
Assuntos
Compostos de Cálcio/química , Cristalização/métodos , Óxidos/química , Oxigênio/química , Paládio/química , Titânio/química , Monóxido de Carbono/química , Catálise , Oxirredução , Difração de Raios XRESUMO
The effects of reactant composition and steam on propane combustion over Pd/LaFe(0.8) Co(0.2) O3 catalyst were investigated. Propane conversion and the oxidation state of palladium were strongly affected by the redox ratio of reactants. Higher propane conversion could be obtained under rich conditions and explained as a complex balance between oxidation and steam reforming. Water produced in the oxidation could promote the propane conversion by steam reforming. However, the presence excess steam would bring about inhibition.