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X-ray photoelectron spectroscopy studies on nickel-tungsten mixed sulfide catalysts

Journal Article · · J. Catal.; (United States)
Among hydrodesulfurization (HDS) catalysts, which generally combine a Group VIA metal sulfide (MoS/sub 2/ or WS/sub 2/) with a Group VIII metal (Co or Ni) considered to be the promoter, the Co-Mo system has so far been the most studied as it has the optimum activity in HDS. However, for other reactions, e.g., hydrodenitrogenation or aromatic and olefin hydrogenation, other couples may have a considerable interest, and among them the Ni-W system. In a combined study by X-ray photoelectron spectroscopy (XPS) and Moessbauer emission spectroscopy (MES), Alstrup et al showed that, by a careful determination of binding energy differences and by comparison of peak shapes, different cobalt phases can be distinguished. In particular, the cobalt 2p binding energy in the Co-Mo-S phase, the presence of which is proved by MES, is similarly ordered 0.5 eV higher than that found in bulk Co/sub 9/S/sub 8/. In this study, which deals with the surface characterization of nickel-tungsten mixed sulfides, the authors describe their attempts to apply the XPS technique to determine (a) a chemical shift between Ni in bulk nickel sulfide with nickel in intimate contact with WS/sub 2/ (Ni decorating WS/sub 2/) and (b) the surface composition with respect to bulk composition. 20 references.
Research Organization:
Universite des Sciences et Techniques de Lille, Villeneuve d'Ascq (France)
OSTI ID:
5203982
Journal Information:
J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 98:1; ISSN JCTLA
Country of Publication:
United States
Language:
English