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XPS study of the surface properties and Ni particle size determination of Ni‐supported catalysts
Author(s) -
Tarditi Ana M.,
Barroso Noelia,
Galetti Agustín E.,
Arrúa Luis A.,
Cornaglia Laura,
Abello María C.
Publication year - 2014
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.5549
Subject(s) - x ray photoelectron spectroscopy , catalysis , inert gas , reducing atmosphere , particle size , atmosphere (unit) , carbon fibers , chemistry , redox , inert , sintering , metal , materials science , inorganic chemistry , chemical engineering , metallurgy , organic chemistry , composite material , physics , composite number , engineering , thermodynamics
The surface properties of Ni/MgAl 2 O 4 catalysts doped with Ce or Pr were analyzed by XPS after treatment in an inert and reductive atmosphere at 400 °C. The Ce‐promoted solids presented the Ce 3+ /Ce 4+ couple on the surface even after treatment in a reductive atmosphere, H 2 (5%)/Ar. The promotion effect of Ce on these solids could be associated with their participation on the carbon deposition‐removal mechanism. Pr‐doped catalysts showed a very high concentration of Pr 3+ under a reductive atmosphere and the redox behavior associated with the carbon removal could be partially inhibited or become slower. The size of the Ni 0 particles after both an inert and a reductive atmosphere was estimated by XPS intensity ratio using the model proposed by Davis. The results obtained from the Davis model showed that an important increase occurred in Ni particle size after treatment in H 2 (5%)/Ar for the Pr‐promoted solids. The metal sintering under reductive atmosphere could be the reason for the higher loss of activity of the Pr‐doped solids under reforming conditions. Copyright © 2014 John Wiley & Sons, Ltd.