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Gaur, Abhijeet; Schumann, Max; Raun, Kristian Viegaard; Stehle, Matthias; Beato, Pablo; Jensen, Anker Degn; Grunwaldt, Jan‐Dierk; Høj, Martin

Operando XAS/XRD and Raman Spectroscopic Study of Structural Changes of the Iron Molybdate Catalyst during Selective Oxidation of Methanol

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  • Medientyp: E-Artikel
  • Titel: Operando XAS/XRD and Raman Spectroscopic Study of Structural Changes of the Iron Molybdate Catalyst during Selective Oxidation of Methanol
  • Beteiligte: Gaur, Abhijeet; Schumann, Max; Raun, Kristian Viegaard; Stehle, Matthias; Beato, Pablo; Jensen, Anker Degn; Grunwaldt, Jan‐Dierk; Høj, Martin
  • Erschienen: Wiley, 2019
  • Erschienen in: ChemCatChem
  • Sprache: Englisch
  • DOI: 10.1002/cctc.201901025
  • ISSN: 1867-3899; 1867-3880
  • Entstehung:
  • Anmerkungen:
  • Beschreibung: <jats:title>Abstract</jats:title><jats:p>The structural changes of an iron molybdate/molybdenum oxide (Mo/Fe=2.0) catalyst for the selective oxidation of methanol to formaldehyde were studied using combined <jats:italic>operando</jats:italic> X‐ray absorption spectroscopy (XAS) and X‐ray diffraction (XRD) as well as <jats:italic>operando</jats:italic> Raman spectroscopy. Under operating conditions, the Mo K‐edge XANES spectra showed a transition from a mixture of α‐MoO<jats:sub>3</jats:sub> and Fe<jats:sub>2</jats:sub>(MoO<jats:sub>4</jats:sub>)<jats:sub>3</jats:sub> towards only Fe<jats:sub>2</jats:sub>(MoO<jats:sub>4</jats:sub>)<jats:sub>3</jats:sub>. XRD and Raman spectroscopy also showed disappearance of the α‐MoO<jats:sub>3</jats:sub> phase with time on stream. The results evidenced that the α‐MoO<jats:sub>3</jats:sub> component evaporated completely, while the Fe<jats:sub>2</jats:sub>(MoO<jats:sub>4</jats:sub>)<jats:sub>3</jats:sub> component remained stable. This was linked to a decrease in catalytic activity. Further studies unraveled that the rate of α‐MoO<jats:sub>3</jats:sub> evaporation increased with increasing MeOH concentration, decreasing O<jats:sub>2</jats:sub> concentration and increasing temperature. The simultaneous measurements of catalytic activity and spectroscopy allowed to derive a structure‐activity relationship showing that α‐MoO<jats:sub>3</jats:sub> evaporation needs to be prevented to optimize MoO<jats:sub>3</jats:sub>‐based catalysts for selective oxidation of methanol.</jats:p>