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Nanoscale evolution with reduction temperature of a Pd/Ce0.8Tb0.2O2-x/LaOx-Al2O3 catalyst

Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica. Facultad de Ciencias. Universidad de Cadiz. Poligono Rio San Pedro s/n. Apdo 40 Puerto Real, Cadiz 11510. Spain

* Departments of Chemistry and Engineering. University of Liverpool, L69 3BX. UK

ABSTRACT: A Pd/Ceo 8Tbo20 2.x/LaOx-Al20 3 catalyst has been studied by HREM and EDS after reduction treatments in the temperature range 623K-1173K. HREM has revealed that up to 973K, both Pd and the Ceo.8Tbo.20 2-x mixed oxide are present as nanosized particles welldispersed over the La-modified alumina support. After reduction at 1173K drastic changes occur: 1) severe sintering of the metallic Pd particles; 2) incorporation of A1 and La into the mixed oxide particles which transform into lanthanide aluminates. According to EDS analysis two different aluminate phases are formed: one Ce,Tb-rich and the other La-rich.