X-Ray Diffraction Study of Palladium Y Zeolite
1973; American Chemical Society; Linguagem: Inglês
10.1021/ba-1973-0121.ch005
ISSN0065-2393
Autores Tópico(s)Zeolite Catalysis and Synthesis
ResumoThe crystal structure of Pd12.5 Y zeolite was determined before and after hydrogen reduction at different temperatures. When the zeolite is evacuated at 600°C, Pd2+ ions are mainly found to occupy SI′ sites within the sodalite cages. Hydrogen adsorption at 25°C results in a complete withdrawal of Pd2+ from SI′ sites. This displacement out of cation sites is attributed to the reduction Pd2+ → Pd(0) consistent with hydrogen volumetric measurements. Reduced palladium remains atomically dispersed inside the sodalite cages up to about 200°C. Between 200 and 300°C, Pd(0) atoms migrate toward the outer surface of the zeolite where they agglomerate into 20-A diameter crystallites.
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