Effect of catalyst preparation on catalytic activity
1988; Elsevier BV; Volume: 37; Linguagem: Inglês
10.1016/s0166-9834(00)80763-0
ISSN1873-3867
AutoresY.-J. Huang, J.A. Schwarz, J. Rodney Diehl, John P. Baltrus,
Tópico(s)Catalysis and Hydrodesulfurization Studies
ResumoIn situ electron spectroscopy for chemical analysis (ESCA) experiments and microreactor studies have been used to examine the apparent occurrence of metal-support interaction on Ni/Al2O3 catalysts; suppression of hydrogen chemisorption does occur subsequent to hydrogen temperature-programmed desorption. The strong metal—support interaction type behavior can be reversed by exposure of the catalyst to oxygen or carbon monoxide. It is demonstrated that the catalyst in the SMSI type state is denuded of surface NiAl2O4 but surface nickel is detectable by ESCA; this nickel does not adsorb hydrogen. Depth profiling reveals an increase in the nickel/aluminum intensity ratio and the partial reappearance of NiAl2O4. A model is proposed to account for the suppression of hydrogen adsorption on nickel. The partial covering of the active center by [AlxOy]n aggregates formed during the thermal disproportionation of NiAl2O4 forms the basis of this model.
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