DFT and kinetic evidences of the preferential CO oxidation pattern of manganese dioxide catalysts in hydrogen stream (PROX)

Arena, Francesco ¹Ferrante, Francesco ²Di Chio, Roberto ¹Bonura, Giuseppe ³Frusteri, Francesco ³Frusteri, Leone ³Prestianni, Antonio ²Morandi, Sara ⁴Martra, Gianmario ⁴Duca, Dario²

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作者信息

1. Univ Messina, Dipartimento Ingn, I-98166 Messina, Italy
2. Univ Palermo, Dipartimento Chim & Fis Emilio Segre, Vle Sci 17, I-90128 Palermo, Italy
3. Ist CNR ITAE Nicola Giordano, Salita S Lucia 39, I-98126 Messina, Italy
4. Univ Torino, Dept Chem, Via P Giuria 7, I-10125 Turin, Italy
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Abstract

The oxidation functionality of Mn(IV) sites has been assessed by density functional theory (DFT) analysis of adsorption and activation energies of CO, H-2 and O-2 on a model Mn4O8 cluster. DFT calculations indicate that Mn (IV) atoms prompt an easy CO conversion to CO2 via a reaction path involving both catalyst and gas-phase oxygen species, while much greater energy barriers hinder H-2 oxidation. Accordingly, a MnCeOx catalyst (Mn-at/Ce-at, 5) with large exposure of Mn(IV) sites shows a remarkable CO oxidation performance at T >= 293 K and no H-2 oxidation activity below 393 K. Empiric kinetics disclose that the catalyst-oxygen abstraction step determines both CO and H-2 oxidation rate, although different activation energies favor the preferential oxidation (PROX) pattern of the studied catalyst (353-423 K). Conversion-selectivity of 100%, high stability during 72 h reaction time and moderate inhibiting effects of water and CO2 feeding reveal the potential of MnO2 materials as efficient, low-cost and robust PROX catalysts.

Key words

DFT analysis/H-2 and CO oxidation/Manganese dioxide catalyst/Reaction mechanism and kinetics/Preferential CO oxidation

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出版年

2022

Applied Catalysis

ISSN：0926-3373

被引量11

参考文献量52

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