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DFT and kinetic evidences of the preferential CO oxidation pattern of manganese dioxide catalysts in hydrogen stream (PROX)
- Publication Year :
- 2022
- Publisher :
- Elsevier B.V., 2022.
-
Abstract
- 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.
- Subjects :
- 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
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Accession number :
- edsair.doi.dedup.....b7ae9bb76b86ae88d54b22f88ec515f7