DFT and kinetic evidences of the preferential CO oxidation pattern of manganese dioxide catalysts in hydrogen stream (PROX)
| Autor: | Francesco Arena, Dario Duca, Gianmario Martra, L. Frusteri, Francesco Ferrante, Roberto Di Chio, Giuseppe Bonura, Francesco Frusteri, Sara Morandi, Antonio Prestianni |
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| Přispěvatelé: | Arena F., Ferrante F., Di Chio R., Bonura G., Frusteri F., Frusteri L., Prestianni A., Morandi S., Martra G., Duca D. |
| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
Hydrogen
Process Chemistry and Technology Inorganic chemistry Kinetics PROX chemistry.chemical_element Preferential CO oxidation Manganese Reaction mechanism and kinetics Oxygen Catalysis and CO oxidation DFT analysis Adsorption chemistry Density functional theory H 2 Manganese dioxide catalyst H2 and CO oxidation General Environmental Science |
| Popis: | The oxidation functionality of Mn(IV) sites has been assessed by density functional theory (DFT) analysis of adsorption and activation energies of CO, H2 and O2 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 H2 oxidation. Accordingly, a MnCeOx catalyst (Mnat/Ceat, 5) with large exposure of Mn(IV) sites shows a remarkable CO oxidation performance at T ≥ 293 K and no H2 oxidation activity below 393 K. Empiric kinetics disclose that the catalyst-oxygen abstraction step determines both CO and H2 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. |
| Databáze: | OpenAIRE |
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