A transient in situ FTIR and XANES study of CO oxidation over Pt/AlO catalysts

Carlsson, Per-Anders; Österlund, Lars; Thormählen, Peter; Palmqvist, Anders; Fridell, Erik; Jansson, Jonas; Skoglundh, Magnus

doi:10.1016/j.jcat.2004.06.009

Cited by 125 publications

(111 citation statements)

References 28 publications

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“…28 The reason why a similar shift is not observed here, despite the simultaneous decline in WLA is likely due to the much lower concentration of CO in the present experiments. The formed CO is preferentially adsorbed on metallic platinum sites indicating an inhomogeneous distribution of surface oxides.…”

Section: Resultssupporting

confidence: 48%

“…The observed shift of the IR band from 2046 to 2069 cm 1 with increasing IR absorption is partly an effect of less back donation of electrons to CO and partly due to increasing repulsive CO-CO lateral interactions with increasing CO coverage, see ref. 28 and references therein. At 280 C, also a band corresponding to CO bridge-bonded to Pt can be observed at about 1850 cm 1 .…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

In Situ Spectroscopic Investigation of Low-Temperature Oxidation of Methane over Alumina-Supported Platinum during Periodic Operation

et al. 2010

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Methane oxidation over Pt/Al 2 O 3 at transient inlet-gas conditions was studied in situ using synchronous EDXAS, FTIRS and mass spectrometry. The employed combination of experimental techniques allows for simultaneous analysis of, respectively, the electronic state of platinum, surface coverage of reaction intermediates/products and catalytic activity/selectivity.By cycling of the feed gas composition between net-oxidizing and net-reducing conditions the activity for methane oxidation can be increased as compared to continuous net-oxidising conditions. Using the white-line area of time-resolved XANES spectra, a quantitative estimation of the surface O/Pt ratio indicates the formation of an inhomogeneous surface oxide on the platinum crystallites during reaction. The obtained temporary high activity can be explained ⇤ To whom correspondence should be addressed 1 through Langmuir-Hinshelwood kinetics and may result either from the formation of a partially oxidized platinum surface that is more effective for methane dissociation or, more likely, from a period with more reactive chemisorbed oxygen prior to oxide formation.

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Section: Resultssupporting

confidence: 48%

Section: Resultsmentioning

confidence: 99%

In Situ Spectroscopic Investigation of Low-Temperature Oxidation of Methane over Alumina-Supported Platinum during Periodic Operation

et al. 2010

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“…Conversion oscillations similar to those observed here were previously observed in single crystal transition metal catalysts, e.g. for Pt, Rh and Ir [20][21][22][23][24]. Usually, oscillations are related to reduction/oxidation cycles, resulting, for example, in non linear rate phenomena arising from oxide or sub-surface layers that deactivate slowly the reactive surface [24].…”

Section: Ht Exafs Screeningsupporting

confidence: 83%

High Throughput In Situ EXAFS Instrumentation for the Automatic Characterization of Materials and Catalysts

Tsapatsaris¹,

Beesley²,

Weiher³

et al. 2007

AIP Conference Proceedings

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Abstract. An XAS data acquisition and control system for the in situ analysis of dynamic materials libraries under control of temperature and gaseous environment has been developed. It was integrated at the SRS in Daresbury, UK, beamline 9.3, using a Si (220) monochromator and a 13 element solid state Ge fluorescence detector. The core of the system is an intelligent X, Y, Z, 0 positioning system coupled to multi-stream quadrupole mass spectrometry analysis (QMS). The system is modular and can be adapted to other synchrotron radiation beamlines. The entire software control was implemented using Labview and allows the scan of a variety of library sizes, in several positions, angles, gas compositions and temperatures with minimal operator intervention. The system was used for the automated characterization of a library of 91 catalyst precursors containing ternary combinations of Cu, Pt, and Au on y-Al 2 0 3 , and for the evaluation and structural characterization of eight Au catalysts supported on A1 2 0 3 and Ti0 2 . Mass spectrometer traces reveal conversion rate oscillations in 6wt % Au/yAl 2 0 3 catalysts. The use of HT experimentation for in situ EXAFS studies demonstrates the feasibility and potential of HT in situ XAFS for synchrotron radiation studies.

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“…Platinum forms two oxides of comparable stability: a CdI 2 -type a-PtO 2 [19] and a rutile-like CaCl 2 -type b-PtO 2 [20]. The formation of Pt-oxide islands or overlayers is corroborated by the large O uptake over Pt(1 1 1) after exposure to ozone [21], by detection with X-ray photoelectron spectroscopy of an oxidic oxygen state after exposure of Pt(1 1 1) to atomic O [22], and by Fourier transformed infrared and X-ray absorption near-edge structure spectroscopy investigations of a model catalyst [23]. Recent surface X-ray diffraction results from the Frenken group further indicate that the a-PtO 2 forms over the Pt(1 1 1) [24] and we hence chose this structure for the oxide phase.…”

Section: Structure Of Three-phase Boundarymentioning

confidence: 79%

Reactivity of a gas/metal/metal-oxide three-phase boundary: CO oxidation at the Pt(111)–c(4×2)-2CO/α-PtO2 phase boundary

Hammer

2005

Chemical Physics Letters

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A transient in situ FTIR and XANES study of CO oxidation over Pt/AlO catalysts

Cited by 125 publications

References 28 publications

In Situ Spectroscopic Investigation of Low-Temperature Oxidation of Methane over Alumina-Supported Platinum during Periodic Operation

In Situ Spectroscopic Investigation of Low-Temperature Oxidation of Methane over Alumina-Supported Platinum during Periodic Operation

High Throughput In Situ EXAFS Instrumentation for the Automatic Characterization of Materials and Catalysts

Reactivity of a gas/metal/metal-oxide three-phase boundary: CO oxidation at the Pt(111)–c(4×2)-2CO/α-PtO2 phase boundary

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