A Water-Promoted Mars-van Krevelen Reaction Dominates Low-Temperature CO Oxidation over Au-Fe 2 O 3 but Not over Au-TiO 2

We provide experimental evidence that is inconsistent with often proposed Langmuir-Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au-Fe O . Passing CO and H O, but no O , over Au-γ-Fe O at 25 °C, we observe significant CO production, inconsistent with LH mechanistic hyp...

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Bibliographic Details
Published in:ACS catalysis 2024-03, Vol.14 (5), p.3191-3197
Main Authors: Holm, Alexander, Davies, Bernadette, Boscolo Bibi, Sara, Moncada, Felix, Halldin-Stenlid, Joakim, Paškevičius, Laurynas, Claman, Vincent, Slabon, Adam, Tai, Cheuk-Wai, Campos Dos-Santos, Egon, Koroidov, Sergey
Format: Article
Language:English
Subjects:
Au Fe2O3
CO oxidation
Langmuir−Hinshelwood
Mars−van Krevelen
mechanism
TiO2
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Summary:We provide experimental evidence that is inconsistent with often proposed Langmuir-Hinshelwood (LH) mechanistic hypotheses for water-promoted CO oxidation over Au-Fe O . Passing CO and H O, but no O , over Au-γ-Fe O at 25 °C, we observe significant CO production, inconsistent with LH mechanistic hypotheses. Experiments with H O further show that previous LH mechanistic proposals cannot account for water-promoted CO oxidation over Au-γ-Fe O . Guided by density functional theory, we instead postulate a water-promoted Mars-van Krevelen (w-MvK) reaction. Our proposed w-MvK mechanism is consistent both with observed CO production in the absence of O and with CO oxidation in the presence of H O and O . In contrast, for Au-TiO , our data is consistent with previous LH mechanistic hypotheses.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.3c05978