Combined spatially resolved operando spectroscopy: New insights into kinetic oscillations of CO oxidation on Pd/Γ-Al 2 O 3

Ellie K. Dann, Emma K. Gibson, C. Richard A. Catlow, Veronica Celorrio, Paul Collier, Tugce Eralp, Monica Amboage, Christopher Hardacre, Cristina Stere, Anna Kroner, Agnes Raj, Scott Rogers, Alexandre Goguet*, Peter P. Wells

*Corresponding author for this work

Research output: Contribution to journalArticle

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Abstract

Spatially resolved, combined energy dispersive EXAFS (EDE) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements have been performed over a fixed catalyst bed of Pd/γ-Al 2 O 3 during kinetic oscillations of CO oxidation. The kinetic oscillations of CO oxidation over Pd (or for that matter Pt or Rh) catalysts are a complicated phenomenon that require characterisation techniques with high time resolution and spatial resolution in order to make links between catalyst structure and surface reactivity. By measuring the extent of Pd oxidation at the nanoparticle surface, from Pd K-edge EDE, and matching this with the CO coverage, from DRIFTS spectra, at multiple positions of the fixed bed reactor it is found that the majority of the catalyst undergoes a sharp transition from the CO poisoned catalyst to the highly active, oxidised Pd surface. This transition occurs initially at the end of the catalyst bed, nearest the outlet, and propagates upstream with increasing temperature of the reactor. The oscillations in Pd surface oxide formation and CO coverage are observed only in the first ∼1 mm of the bed, which gives rise to oscillations in CO 2 and O 2 concentrations observed by end-pipe mass spectrometry after the light-off temperature. The catalyst initially exists as less active, CO poisoned metallic Pd nanoparticles before light-off which transition to a highly active state after light-off when the Pd nanoparticle surface becomes dominated by chemisorbed oxygen. Kinetic oscillations only occur at the front of the catalyst bed where there is sufficient concentration of CO in the gas phase to compete with O 2 for adsorption sites at the catalyst surface. We demonstrate the complex nature of the evolving catalyst structure and surface reactivity during catalytic operation and the need for spatially resolved operando methods for understanding and optimising catalyst technologies.

Original languageEnglish
Pages (from-to)201-208
Number of pages8
JournalJournal of Catalysis
Volume373
Early online date08 Apr 2019
DOIs
Publication statusPublished - 01 May 2019

Fingerprint

Carbon Monoxide
Spectroscopy
catalysts
Oxidation
oscillations
oxidation
Catalysts
Kinetics
kinetics
spectroscopy
beds
Nanoparticles
nanoparticles
Fourier transform infrared spectroscopy
reactivity
reactors
reflectance
outlets
Oxides
upstream

Keywords

  • CO oxidation
  • DRIFTS
  • Operando spectroscopy
  • Pd/Al O
  • XAFS

Cite this

Dann, Ellie K. ; Gibson, Emma K. ; Catlow, C. Richard A. ; Celorrio, Veronica ; Collier, Paul ; Eralp, Tugce ; Amboage, Monica ; Hardacre, Christopher ; Stere, Cristina ; Kroner, Anna ; Raj, Agnes ; Rogers, Scott ; Goguet, Alexandre ; Wells, Peter P. / Combined spatially resolved operando spectroscopy: New insights into kinetic oscillations of CO oxidation on Pd/Γ-Al 2 O 3. In: Journal of Catalysis. 2019 ; Vol. 373. pp. 201-208.
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abstract = "Spatially resolved, combined energy dispersive EXAFS (EDE) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements have been performed over a fixed catalyst bed of Pd/γ-Al 2 O 3 during kinetic oscillations of CO oxidation. The kinetic oscillations of CO oxidation over Pd (or for that matter Pt or Rh) catalysts are a complicated phenomenon that require characterisation techniques with high time resolution and spatial resolution in order to make links between catalyst structure and surface reactivity. By measuring the extent of Pd oxidation at the nanoparticle surface, from Pd K-edge EDE, and matching this with the CO coverage, from DRIFTS spectra, at multiple positions of the fixed bed reactor it is found that the majority of the catalyst undergoes a sharp transition from the CO poisoned catalyst to the highly active, oxidised Pd surface. This transition occurs initially at the end of the catalyst bed, nearest the outlet, and propagates upstream with increasing temperature of the reactor. The oscillations in Pd surface oxide formation and CO coverage are observed only in the first ∼1 mm of the bed, which gives rise to oscillations in CO 2 and O 2 concentrations observed by end-pipe mass spectrometry after the light-off temperature. The catalyst initially exists as less active, CO poisoned metallic Pd nanoparticles before light-off which transition to a highly active state after light-off when the Pd nanoparticle surface becomes dominated by chemisorbed oxygen. Kinetic oscillations only occur at the front of the catalyst bed where there is sufficient concentration of CO in the gas phase to compete with O 2 for adsorption sites at the catalyst surface. We demonstrate the complex nature of the evolving catalyst structure and surface reactivity during catalytic operation and the need for spatially resolved operando methods for understanding and optimising catalyst technologies.",
keywords = "CO oxidation, DRIFTS, Operando spectroscopy, Pd/Al O, XAFS",
author = "Dann, {Ellie K.} and Gibson, {Emma K.} and Catlow, {C. Richard A.} and Veronica Celorrio and Paul Collier and Tugce Eralp and Monica Amboage and Christopher Hardacre and Cristina Stere and Anna Kroner and Agnes Raj and Scott Rogers and Alexandre Goguet and Wells, {Peter P.}",
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Dann, EK, Gibson, EK, Catlow, CRA, Celorrio, V, Collier, P, Eralp, T, Amboage, M, Hardacre, C, Stere, C, Kroner, A, Raj, A, Rogers, S, Goguet, A & Wells, PP 2019, 'Combined spatially resolved operando spectroscopy: New insights into kinetic oscillations of CO oxidation on Pd/Γ-Al 2 O 3', Journal of Catalysis, vol. 373, pp. 201-208. https://doi.org/10.1016/j.jcat.2019.03.037

Combined spatially resolved operando spectroscopy: New insights into kinetic oscillations of CO oxidation on Pd/Γ-Al 2 O 3. / Dann, Ellie K.; Gibson, Emma K.; Catlow, C. Richard A.; Celorrio, Veronica; Collier, Paul; Eralp, Tugce; Amboage, Monica; Hardacre, Christopher; Stere, Cristina; Kroner, Anna; Raj, Agnes; Rogers, Scott; Goguet, Alexandre; Wells, Peter P.

In: Journal of Catalysis, Vol. 373, 01.05.2019, p. 201-208.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Combined spatially resolved operando spectroscopy: New insights into kinetic oscillations of CO oxidation on Pd/Γ-Al 2 O 3

AU - Dann, Ellie K.

AU - Gibson, Emma K.

AU - Catlow, C. Richard A.

AU - Celorrio, Veronica

AU - Collier, Paul

AU - Eralp, Tugce

AU - Amboage, Monica

AU - Hardacre, Christopher

AU - Stere, Cristina

AU - Kroner, Anna

AU - Raj, Agnes

AU - Rogers, Scott

AU - Goguet, Alexandre

AU - Wells, Peter P.

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Spatially resolved, combined energy dispersive EXAFS (EDE) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements have been performed over a fixed catalyst bed of Pd/γ-Al 2 O 3 during kinetic oscillations of CO oxidation. The kinetic oscillations of CO oxidation over Pd (or for that matter Pt or Rh) catalysts are a complicated phenomenon that require characterisation techniques with high time resolution and spatial resolution in order to make links between catalyst structure and surface reactivity. By measuring the extent of Pd oxidation at the nanoparticle surface, from Pd K-edge EDE, and matching this with the CO coverage, from DRIFTS spectra, at multiple positions of the fixed bed reactor it is found that the majority of the catalyst undergoes a sharp transition from the CO poisoned catalyst to the highly active, oxidised Pd surface. This transition occurs initially at the end of the catalyst bed, nearest the outlet, and propagates upstream with increasing temperature of the reactor. The oscillations in Pd surface oxide formation and CO coverage are observed only in the first ∼1 mm of the bed, which gives rise to oscillations in CO 2 and O 2 concentrations observed by end-pipe mass spectrometry after the light-off temperature. The catalyst initially exists as less active, CO poisoned metallic Pd nanoparticles before light-off which transition to a highly active state after light-off when the Pd nanoparticle surface becomes dominated by chemisorbed oxygen. Kinetic oscillations only occur at the front of the catalyst bed where there is sufficient concentration of CO in the gas phase to compete with O 2 for adsorption sites at the catalyst surface. We demonstrate the complex nature of the evolving catalyst structure and surface reactivity during catalytic operation and the need for spatially resolved operando methods for understanding and optimising catalyst technologies.

AB - Spatially resolved, combined energy dispersive EXAFS (EDE) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements have been performed over a fixed catalyst bed of Pd/γ-Al 2 O 3 during kinetic oscillations of CO oxidation. The kinetic oscillations of CO oxidation over Pd (or for that matter Pt or Rh) catalysts are a complicated phenomenon that require characterisation techniques with high time resolution and spatial resolution in order to make links between catalyst structure and surface reactivity. By measuring the extent of Pd oxidation at the nanoparticle surface, from Pd K-edge EDE, and matching this with the CO coverage, from DRIFTS spectra, at multiple positions of the fixed bed reactor it is found that the majority of the catalyst undergoes a sharp transition from the CO poisoned catalyst to the highly active, oxidised Pd surface. This transition occurs initially at the end of the catalyst bed, nearest the outlet, and propagates upstream with increasing temperature of the reactor. The oscillations in Pd surface oxide formation and CO coverage are observed only in the first ∼1 mm of the bed, which gives rise to oscillations in CO 2 and O 2 concentrations observed by end-pipe mass spectrometry after the light-off temperature. The catalyst initially exists as less active, CO poisoned metallic Pd nanoparticles before light-off which transition to a highly active state after light-off when the Pd nanoparticle surface becomes dominated by chemisorbed oxygen. Kinetic oscillations only occur at the front of the catalyst bed where there is sufficient concentration of CO in the gas phase to compete with O 2 for adsorption sites at the catalyst surface. We demonstrate the complex nature of the evolving catalyst structure and surface reactivity during catalytic operation and the need for spatially resolved operando methods for understanding and optimising catalyst technologies.

KW - CO oxidation

KW - DRIFTS

KW - Operando spectroscopy

KW - Pd/Al O

KW - XAFS

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