Open AccessNature of cobalt species during the in situ sulfurization of Co(Ni)Mo/Al 2 O 3 hydrodesulfurization catalysts
Author(s) -
al Samarai Mustafa,
van Oversteeg Christa H. M.,
Delgado-Jaime Mario Ulises,
Weng Tsu-Chien,
Sokaras Dimosthenis,
Liu Boyang,
van der Linden Marte,
van der Eerden Ad M. J.,
Vogt Eelco T. C.,
Weckhuysen Bert M.,
de Groot Frank M. F.
Publication year - 2019
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577519002546
Subject(s) - cobalt , x ray absorption spectroscopy , hydrodesulfurization , catalysis , molybdenum , valence (chemistry) , sulfide , nickel , chemistry , absorption spectroscopy , inorganic chemistry , crystallography , analytical chemistry (journal) , physics , organic chemistry , chromatography , quantum mechanics , biochemistry
The evolution in local structure and electronic properties of cobalt was investigated during in situ sulfurization. Using a combination of 1 s X‐ray absorption (XAS) and 1 s 3 p resonant inelastic X‐ray scattering (RIXS), the valence, coordination and symmetry of cobalt ions were tracked in two cobalt‐promoted molybdenum oxide precursors of the hydrodesulfurization catalyst system, namely Co–Mo/Al 2 O 3 and Co–Ni–Mo/Al 2 O 3 . Extended X‐ray absorption fine structure shows that the Co—O bonds were replaced with Co—S bonds as a function of reaction temperature. The cobalt K pre‐edge intensity shows that the symmetry of cobalt was modified from Co 3+ O h and Co 2+ O h to a Co 2+ ion where the inversion symmetry is broken, in agreement with a square‐pyramidal site. The 1 s 3 p RIXS data revealed the presence of an intermediate cobalt oxy‐sulfide species. This species was not detected from XAS and was determined from the increased information obtained from the 1 s 3 p RIXS data. The cobalt XAS and RIXS data show that nickel has a significant influence on the formation of the cobalt oxy‐sulfide intermediate species prior to achieving the fully sulfided state at T > 400°C.