The quick EXAFS setup at beamline P64 at PETRA III for up to 200 spectra per second

Bornmann, Benjamin; Kläs, Jonas; Müller, Oliver; Lützenkirchen‐Hecht, Dirk; Frahm, R.

doi:10.1063/1.5084609

Cited by 21 publications

(20 citation statements)

References 4 publications

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“…QEXAFS spectroscopy was used to collect spectra with a frequency of 1–10 Hz, resulting in 2–20 spectra per second tracking the electronic properties of Pt during the rapid gas phase changes and transient light-off experiments. The polychromatic X-ray beam from the tapered undulator was tuned to the Pt L 3 edge by a liquid nitrogen cooled Si(111) channel-cut crystal as monochromator . Special gridded ion chambers were used to optimize the rise time for the fast measurements.…”

Section: Methodsmentioning

confidence: 99%

“…Combined In Situ/Operando Infrared Thermography and X-ray Absorption Spectroscopy. Combined infrared thermography (IRT) and X-ray absorption spectroscopy (XAS) investigations were performed at the P64 beamline 43 at DESY (Hamburg, Germany). The experiments were conducted in a quartz capillary microreactor with plugflow geometry, used as in situ cell and heated by a hot air gas blower (FMB Oxford).…”

Section: Materials and Basic Characterizationmentioning

confidence: 99%

“…The polychromatic X-ray beam from the tapered undulator was tuned to the Pt L 3 edge by a liquid nitrogen cooled Si(111) channel-cut crystal as monochromator. 43 Special gridded ion chambers 46 were used to optimize the rise time for the fast measurements. With a beam size of 0.5 mm (horizontal) × 1.0 mm (vertical), 5 points along the catalyst bed were selected.…”

Section: Materials and Basic Characterizationmentioning

confidence: 99%

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Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO₂ Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Maurer

Gänzler

Lott

et al. 2021

Ind. Eng. Chem. Res.

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Reductive treatments with pulses of CO-rich atmosphere have been used to increase and maintain the low temperature activity of a Pt/CeO2-based oxidation catalyst. A combination of operando infrared thermography and spatiotemporal-resolved quick scanning extended X-ray absorption fine structure spectroscopy on a fixed bed microreactor unraveled that, apart from the pulse length, the reaction atmosphere, and the reactor temperature, also the emerging reaction heat during such activating pulses has a strong influence on the structure and catalytic performance of CO and propylene conversion in the axial direction of a fixed-bed and a monolithic reactor. The reductive pulse activation led to an increase of the integral catalyst activity as well as to the generation of zones of different particle sizes along the catalyst bed. In the case of an activation temperature between 250 and 350 °C and pulse lengths between 5 and 30 s, a hotspot of more than 80 K was observed at the beginning of the catalyst bed. Spatially resolved X-ray absorption spectroscopy indicates that larger and more reduced Pt particles are formed particularly at the beginning of the catalyst bed, whereas its subsequent part is less affected. Both the length of the reductive pulses and activation temperature have a distinct influence on the noble metal particle size. On the basis of these results, a Pt/CeO2 based honeycomb shaped substrate was activated in a similar manner. Spatially resolved gas phase profiling showed different reaction rates at the beginning of the reactor, which indicates that the concept can be transferred also to industrially relevant catalysts. In the future, such an activation procedure might open up the door to a new class of operation strategies, by which individual zones generated in the catalyst bed could be assigned for removal of specific pollutants in the exhaust stream.

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Section: Methodsmentioning

confidence: 99%

Section: Materials and Basic Characterizationmentioning

confidence: 99%

Section: Materials and Basic Characterizationmentioning

confidence: 99%

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Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO₂ Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Maurer

Gänzler

Lott

et al. 2021

Ind. Eng. Chem. Res.

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“…Pt‐N‐400 and Pt‐N‐400‐250H were measured at P64 beamline of the PETRA III synchrotron (DESY, Hamburg, Germany) operating in the QEXAFS mode. The average Pt oxidation state was determined by a linear combination analysis (LCA) of the XANES spectra using internal references from QEXAFS datasets in a fitting range of 11544–11594 eV using JAQ software . To translate the relative fractions obtained from the QEXAFS analysis to the oxidation state of Pt the internal reference spectra were exported and evaluated using LCA with Pt foil and PtO 2 reference spectra in Athena.…”

Section: Methodsmentioning

confidence: 99%

Insight into the Nature of Active Species of Pt/Al₂O₃ Catalysts for low Temperature NH₃ Oxidation

et al. 2019

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Two series of Pt/γ-Al 2 O 3 catalysts for low temperature NH 3 oxidation were prepared using Pt(NO 3 ) 4 and H 2 PtCl 6 precursors. Using both precursors results in the formation of small Pt particles (d < 1.5 nm), however, Cl-containing Pt precursors give a higher fraction of highly dispersed Pt species. Such species show high stability against thermal or H 2 treatment probably due to the presence of a substantial amount of chlorine on the surface. Treatment of the samples prepared from Pt(NO 3 ) 4 with H 2 leads to the formation of metallic Pt nanoparticles accompanied by the improvement of catalytic activity in NH 3 oxidation at T < 200°C. The main products of ammonia oxidation at temperatures below 250°C were molecular nitrogen and nitrous oxide with the N 2 selectivity reaching 80 %. Operando XANES/ EXAFS revealed that even after H 2 pretreatment at least 40 % of Pt surface remains in oxidized state under reaction conditions resulting in the appearance of N 2 O as a by-product.

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“…The experiments described here were conducted at beamline X10DA (SuperXAS beamline, Paul Scherrer Institute, Swiss Light Source) [ 32 ] and the Quick‐EXAFS endstation P64 at the PETRA III storage ring (DESY, Hamburg, Germany). [ 33 ] At both beamlines, oscillating Si(111) channel‐cut monochromators were used, and N 2 gas‐filled ionization chambers were used as detectors for the incident and the reflected intensities. Slit systems were used to define the incident beam (0.1 mm vertical (v) × 1 mm horizontal (h) size) and clean the reflected beam (0.3 mm (v) × 2 mm (h)), respectively.…”

Section: Methodsmentioning

confidence: 99%

Time‐Resolved Grazing Incidence X‐Ray Absorption Spectroscopy for the In Situ Investigation of the Initial Stages of Sputter‐Deposited Copper Thin Films

Lützenkirchen‐Hecht

Stötzel

Just

et al. 2021

Physica Status Solidi (a)

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The sputter deposition and the growth of thin copper films on float glass substrates are in situ studied using grazing incidence, reflection mode X‐ray absorption fine structure spectroscopy with subsecond time resolution. The experimental data are compared with model calculations, assuming the presence of crystalline, face‐centered cubic metallic Cu nanostructures. From a detailed analysis of the measured spectra, the film thickness as well as the surface roughness is determined, leading to a detailed understanding of the films growth as a function of the sputter deposition time. In particular, different stages of film growth can clearly be distinguished from the fits of the experimental data. The results suggest the formation of isolated, approximately nm‐sized copper clusters in the initial phase of the film deposition for the first few seconds, a coalescence phase with a nominal thickness of ≈1.5−2.8 nm, constant roughness of about 1.4 nm for the subsequent ≈5 s, and finally 3D growth of the Cu crystallites in the film for later stages of film growth. Further prospects of the methodology are given.

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The quick EXAFS setup at beamline P64 at PETRA III for up to 200 spectra per second

Cited by 21 publications

References 4 publications

Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO₂ Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO₂ Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Insight into the Nature of Active Species of Pt/Al₂O₃ Catalysts for low Temperature NH₃ Oxidation

Time‐Resolved Grazing Incidence X‐Ray Absorption Spectroscopy for the In Situ Investigation of the Initial Stages of Sputter‐Deposited Copper Thin Films

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The quick EXAFS setup at beamline P64 at PETRA III for up to 200 spectra per second

Cited by 21 publications

References 4 publications

Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO2 Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO2 Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Insight into the Nature of Active Species of Pt/Al2O3 Catalysts for low Temperature NH3 Oxidation

Time‐Resolved Grazing Incidence X‐Ray Absorption Spectroscopy for the In Situ Investigation of the Initial Stages of Sputter‐Deposited Copper Thin Films

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Product

Resources

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Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO₂ Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Spatiotemporal Investigation of the Temperature and Structure of a Pt/CeO₂ Oxidation Catalyst for CO and Hydrocarbon Oxidation during Pulse Activation

Insight into the Nature of Active Species of Pt/Al₂O₃ Catalysts for low Temperature NH₃ Oxidation