Transition metal doping of Pd(1 1 1) for the NO + CO reaction

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Abstract

The replacement of platinum group metals by non-noble metals has attracted significant attention in the field of three-way catalysis. Here, we use DFT calculations to comprehensively study NO reduction by CO and CO oxidation on Pd(1 1 1) and transition metal doped Pd(1 1 1). Whilst direct NO dissociation is very difficult on metallic Pd(1 1 1), doping with transition metals can substantially lower the reaction barrier for NO dissociation. The lowest barrier is predicted for Ti-doped Pd(1 1 1). An electronic structure analysis shows that the low barrier is due to the strong adsorption of N and O on surface sites involving Ti atoms. It relates to strong hybridization of the N and O orbitals with the half-filled d-band of the metallic surface. At the same time, the anti-bonding states are shifted above the Fermi level, which further strengthens the adsorption of N and O. A Brønsted-Evans-Polanyi relation for NO dissociation on TM-doped Pd(1 1 1) surfaces is identified. The complete reaction pathway for N2, N2O and CO2 formation on Pd(1 1 1) and Ti-doped Pd(1 1 1) was considered. Besides more facile NO dissociation, the energy barrier for CO oxidation is decreased for the Ti-doped surface. Microkinetics simulations confirm that the activity and selectivity for NO reduction and CO oxidation are drastically improved after Ti doping. Our findings indicate that doping of Pd with non-noble metal can further improve the performance of three-way catalysts.

Original languageEnglish
Pages (from-to)154-163
Number of pages10
JournalJournal of Catalysis
Volume363
DOIs
Publication statusPublished - 1 Jul 2018

Fingerprint

Carbon Monoxide
Transition metals
transition metals
Doping (additives)
dissociation
Metals
Oxidation
oxidation
metals
Adsorption
adsorption
Energy barriers
Platinum
Fermi level
Discrete Fourier transforms
Catalysis
catalysis
Electronic structure
platinum
Thermodynamic properties

Keywords

  • DFT calculation
  • NO + CO reaction
  • Pd(1 1 1)
  • Transition metal doping

Cite this

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title = "Transition metal doping of Pd(1 1 1) for the NO + CO reaction",
abstract = "The replacement of platinum group metals by non-noble metals has attracted significant attention in the field of three-way catalysis. Here, we use DFT calculations to comprehensively study NO reduction by CO and CO oxidation on Pd(1 1 1) and transition metal doped Pd(1 1 1). Whilst direct NO dissociation is very difficult on metallic Pd(1 1 1), doping with transition metals can substantially lower the reaction barrier for NO dissociation. The lowest barrier is predicted for Ti-doped Pd(1 1 1). An electronic structure analysis shows that the low barrier is due to the strong adsorption of N and O on surface sites involving Ti atoms. It relates to strong hybridization of the N and O orbitals with the half-filled d-band of the metallic surface. At the same time, the anti-bonding states are shifted above the Fermi level, which further strengthens the adsorption of N and O. A Br{\o}nsted-Evans-Polanyi relation for NO dissociation on TM-doped Pd(1 1 1) surfaces is identified. The complete reaction pathway for N2, N2O and CO2 formation on Pd(1 1 1) and Ti-doped Pd(1 1 1) was considered. Besides more facile NO dissociation, the energy barrier for CO oxidation is decreased for the Ti-doped surface. Microkinetics simulations confirm that the activity and selectivity for NO reduction and CO oxidation are drastically improved after Ti doping. Our findings indicate that doping of Pd with non-noble metal can further improve the performance of three-way catalysts.",
keywords = "DFT calculation, NO + CO reaction, Pd(1 1 1), Transition metal doping",
author = "L. Zhang and I.A.W. Filot and Y. Su and J. Liu and E.J.M. Hensen",
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month = "7",
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Transition metal doping of Pd(1 1 1) for the NO + CO reaction. / Zhang, L.; Filot, I.A.W.; Su, Y.; Liu, J.; Hensen, E.J.M.

In: Journal of Catalysis, Vol. 363, 01.07.2018, p. 154-163.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Transition metal doping of Pd(1 1 1) for the NO + CO reaction

AU - Zhang, L.

AU - Filot, I.A.W.

AU - Su, Y.

AU - Liu, J.

AU - Hensen, E.J.M.

PY - 2018/7/1

Y1 - 2018/7/1

N2 - The replacement of platinum group metals by non-noble metals has attracted significant attention in the field of three-way catalysis. Here, we use DFT calculations to comprehensively study NO reduction by CO and CO oxidation on Pd(1 1 1) and transition metal doped Pd(1 1 1). Whilst direct NO dissociation is very difficult on metallic Pd(1 1 1), doping with transition metals can substantially lower the reaction barrier for NO dissociation. The lowest barrier is predicted for Ti-doped Pd(1 1 1). An electronic structure analysis shows that the low barrier is due to the strong adsorption of N and O on surface sites involving Ti atoms. It relates to strong hybridization of the N and O orbitals with the half-filled d-band of the metallic surface. At the same time, the anti-bonding states are shifted above the Fermi level, which further strengthens the adsorption of N and O. A Brønsted-Evans-Polanyi relation for NO dissociation on TM-doped Pd(1 1 1) surfaces is identified. The complete reaction pathway for N2, N2O and CO2 formation on Pd(1 1 1) and Ti-doped Pd(1 1 1) was considered. Besides more facile NO dissociation, the energy barrier for CO oxidation is decreased for the Ti-doped surface. Microkinetics simulations confirm that the activity and selectivity for NO reduction and CO oxidation are drastically improved after Ti doping. Our findings indicate that doping of Pd with non-noble metal can further improve the performance of three-way catalysts.

AB - The replacement of platinum group metals by non-noble metals has attracted significant attention in the field of three-way catalysis. Here, we use DFT calculations to comprehensively study NO reduction by CO and CO oxidation on Pd(1 1 1) and transition metal doped Pd(1 1 1). Whilst direct NO dissociation is very difficult on metallic Pd(1 1 1), doping with transition metals can substantially lower the reaction barrier for NO dissociation. The lowest barrier is predicted for Ti-doped Pd(1 1 1). An electronic structure analysis shows that the low barrier is due to the strong adsorption of N and O on surface sites involving Ti atoms. It relates to strong hybridization of the N and O orbitals with the half-filled d-band of the metallic surface. At the same time, the anti-bonding states are shifted above the Fermi level, which further strengthens the adsorption of N and O. A Brønsted-Evans-Polanyi relation for NO dissociation on TM-doped Pd(1 1 1) surfaces is identified. The complete reaction pathway for N2, N2O and CO2 formation on Pd(1 1 1) and Ti-doped Pd(1 1 1) was considered. Besides more facile NO dissociation, the energy barrier for CO oxidation is decreased for the Ti-doped surface. Microkinetics simulations confirm that the activity and selectivity for NO reduction and CO oxidation are drastically improved after Ti doping. Our findings indicate that doping of Pd with non-noble metal can further improve the performance of three-way catalysts.

KW - DFT calculation

KW - NO + CO reaction

KW - Pd(1 1 1)

KW - Transition metal doping

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