In situ Moessbauer emission spectroscopy studies of unsupported and supported sulfided Co-Mo hydrodesulfurization catalysts: evidence for and nature of a Co-Mo-S phase

Journal Article · Wed Apr 01 00:00:00 EST 1981 · J. Catal.; (United States)

OSTI ID:6367261

Topsoee, H ^[1]; Clausen, B S; Candia, R; Wivel, C; Moerup, S

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1. Haldor Topsoee Research Labs., Lyngby, Denmark

Information regarding the structure and type of phases present in sulfided alumina-supported, as well as unsupported, Co-Mo catalysts is obtained from in situ Moessbauer emission spectroscopy (MES) studies. The results give the first direct evidence of the presence of a Co-Mo-S phase in alumina-supported and unsupported catalysts with similar Co/Mo ratios. Information regarding the nature of the Co-Mo-S phase is obtained from a detailed study of the Moessbauer parameters, their temperature dependence, and their sensitivity to changes in the gaseous environment. Previously proposed structural models cannot explain all the observed features of the Co-Mo-S phase. It is proposed that in alumina-supported catalysts the Co-Mo-S phase is present as single S-Mo-S slabs (i.e., one layer of the MoS/sub 2/ structure) with cobalt most likely present at molybdenum sites. For unsupported catalysts the Co-Mo-S phase consists of several slabs with bulk MoS/sub 2/-like structure. The present observations suggest that the previously observed similarities between supported and unsupported catalysts are associated with the presence of the Co-Mo-S phase in both catalyst systems. A possible reaction mechanism for hydrodesulfurization involving cobalt in the Co-Mo-S phase is proposed. Information regarding other phases in the catalysts is obtained by MES studies of Co/Al/sub 2/O/sub 3/, CoMo/sub 2/S/sub 4/, Co/sub 9/S/sub 8/, CoS/sub 2/, Co/sub 3/S/sub 4/, and CoS/sub 1+x/ samples. It is observed that for a sulfided Co-Mo/Al/sub 2/O/sub 3/ catalyst with a composition typical of those used industrially, part of the cobalt is located in the alumina. For unsupported catalysts the effect of changing the cobalt concentration and preparation method is investigated and it is observed that under certain conditions also the thermodynamically stable cobalt sulfide, Co/sub 9/S/sub 8/, may be formed.

• OSTI ID: 6367261
• Journal Information: J. Catal.; (United States), Vol. 68:2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
CATALYSTS
CHEMICAL COMPOSITION
PHASE STUDIES
DESULFURIZATION
ALUMINIUM OXIDES
CATALYST SUPPORTS
COBALT
COBALT SULFIDES
EMISSION SPECTROSCOPY
MOLYBDENUM
MOLYBDENUM SULFIDES
SULFIDES
ALUMINIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
COBALT COMPOUNDS
ELEMENTS
METALS
MOLYBDENUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METALS
SPECTROSCOPY
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
020400* - Petroleum- Processing