Unraveling surface and bulk dynamics of iron(III) molybdate during oxidative dehydrogenation using operando and transient spectroscopies

Iron(III) molybdate (Fe 2 (MoO 4 ) 3 ) is a commercial catalyst for the oxidative dehydrogenation (ODH) of methanol, but it has recently been shown to be relevant for other substrates as well. Despite its commercial use, a detailed mechanistic understanding of Fe 2 (MoO 4 ) 3 catalysts at the surfac...

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Bibliographic Details
Published in:Communications chemistry 2023-10, Vol.6 (1), p.230-230, Article 230
Main Authors: Schumacher, Leon, Radtke, Mariusz, Welzenbach, Jan, Hess, Christian
Format: Article
Language:English
Subjects:
639/301/930/527/1821
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639/638/77/887
Catalysis
Catalysts
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Dehydrogenation
Infrared spectroscopy
Iron
Methanol
Oxidation
Oxygen
Raman spectroscopy
Spectrum analysis
Substrates
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Summary:Iron(III) molybdate (Fe 2 (MoO 4 ) 3 ) is a commercial catalyst for the oxidative dehydrogenation (ODH) of methanol, but it has recently been shown to be relevant for other substrates as well. Despite its commercial use, a detailed mechanistic understanding of Fe 2 (MoO 4 ) 3 catalysts at the surface and in the bulk has been lacking, largely hampered by the lack of suitable spectroscopic methods, directly applicable under reaction conditions. Using propane ODH as an example, we highlight the potential of operando Raman and impedance spectroscopy combined with transient IR spectroscopy, to identify surface active sites and monitor the hydrogen transfer and oxygen dynamics. By comparison with the behavior of reference compounds (MoO 3 , MoO x /Fe 2 O 3 ) a mechanistic model is proposed. The presence of iron greatly influences the reactivity behavior via oxygen diffusion but is moderated in its oxidative capacity by surface MoO x . Our approach directly elucidates fundamental properties of Fe 2 (MoO 4 ) 3 of general importance to selective oxidation catalysis. Iron(III) molybdate is a commercial catalyst for selective oxidations such as oxidative dehydrogenation of methanol, but our understanding of the involved (sub)surface and bulk conversion processes remains limited. Here, the authors use modulation excitation IR, operando impedance, and multiwavelength Raman spectroscopy to show the mode of operation of this important catalyst.
ISSN:2399-3669
2399-3669
DOI:10.1038/s42004-023-01028-8