Unraveling the redox behavior of a CoMoS hydrodesulfurization catalyst : a scanning transmission x-ray microscopy study in the tender x-ray range

M. Al Samarai, F. Meirer, C. Karunakaran, J. Wang, E.T.C. Vogt, H.W. Zandbergen, T. Weber, B.M. Weckhuysen, F.M.F. de Groot

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)

Abstract

We visualize the elemental zoning in an alumina-supported cobalt molybdenum sulfide (CoMoS) catalyst with scanning transmission X-ray microscopy (STXM). We use the Canadian Light Source beamline 10-ID’s (SM) unique combination of soft X-ray and tender X-ray STXM to determine the spatial variation of Co, Al, Mo, and S species. The results clearly show the correlation between cobalt and molybdenum and the anticorrelation between cobalt and alumina, confirming that Co is closely associated with the MoS2 phase. The tender X-ray STXM images show that the fresh catalyst particle contains a 50 nm ring of molybdenum oxide encapsulating the supported MoS2 phase. After the reduction at 200 °C with H2, this oxide rim disappears and a uniform MoS2 distribution is found. Upon oxidation at 400 °C, the sulfur disappears from the catalyst sample and molybdenum is oxidized from a MoIV sulfide to a mainly tetrahedral MoVI oxide, while cobalt keeps its divalent nature and changes from a CoII sulfide to a CoII oxide.
Original languageEnglish
Pages (from-to)2530-2536
JournalJournal of Physical Chemistry C
Volume119
DOIs
Publication statusPublished - 2015

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