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Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique. / Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram; Nachtegaal, Maarten; Grunwaldt, Jan-Dierk.

In: Journal of Physical Chemistry Part C: Nanomaterials and Interfaces, Vol. 116, No. 1, 2012, p. 599-609.

Publication: Research - peer-reviewJournal article – Annual report year: 2012

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Stoetzel, Jan; Frahm, Ronald; Kimmerle, Bertram; Nachtegaal, Maarten; Grunwaldt, Jan-Dierk / Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique.

In: Journal of Physical Chemistry Part C: Nanomaterials and Interfaces, Vol. 116, No. 1, 2012, p. 599-609.

Publication: Research - peer-reviewJournal article – Annual report year: 2012

Bibtex

@article{76798f766641467ba8e408edbeb64c6b,
title = "Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique",
publisher = "American Chemical Society",
author = "Jan Stoetzel and Ronald Frahm and Bertram Kimmerle and Maarten Nachtegaal and Jan-Dierk Grunwaldt",
year = "2012",
doi = "10.1021/jp2052294",
volume = "116",
number = "1",
pages = "599--609",
journal = "Journal of Physical Chemistry Part C: Nanomaterials and Interfaces",
issn = "1932-7447",

}

RIS

TY - JOUR

T1 - Oscillatory Behavior during the Catalytic Partial Oxidation of Methane: Following Dynamic Structural Changes of Palladium Using the QEXAFS Technique

A1 - Stoetzel,Jan

A1 - Frahm,Ronald

A1 - Kimmerle,Bertram

A1 - Nachtegaal,Maarten

A1 - Grunwaldt,Jan-Dierk

AU - Stoetzel,Jan

AU - Frahm,Ronald

AU - Kimmerle,Bertram

AU - Nachtegaal,Maarten

AU - Grunwaldt,Jan-Dierk

PB - American Chemical Society

PY - 2012

Y1 - 2012

N2 - Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were investigated using spatially and time-resolved in situ quick scanning X-ray absorption spectroscopy with online mass spectrometry. The dynamic methane conversion oscillated between an inactive state, where only combustion occurred, and an active state, after ignition, where partial oxidation of methane as a combination of total oxidation and reforming in the catalytic capillary reactor was observed. This change in catalytic performance was directly linked to changes in the oxidation state of the Pd/Al2O3 catalysts at different positions along the catalytic reactor. During the ignition of the catalytic partial oxidation of methane, the catalyst reduced from the end to the beginning of the catalyst bed and oxidized again toward the end as soon as the entire catalyst bed was reduced. On an entirely oxidized catalyst bed, only total oxidation of methane was observed and consumed the oxygen until the conditions at the end of the catalyst bed lead to a reduction of the catalyst bed again and a new cycle began with partial oxidation. Prior to the oxidation of the catalyst, a temporary lattice expansion appeared, which could be assigned to carbon intercalation into the palladium lattice. Furthermore, a sintering of the Pd particles at increasing age of the catalyst was observed, which leads to a lower oscillation frequency. Effects of particle size, oven temperature, and oxygen/methane ratio on the oscillation behavior were studied in detail. The deactivation period (reoxidation of Pd) was much less influenced by the oven temperature than the ignition behavior of the catalytic partial oxidation of methane. This indicates that deactivation is caused by an autoreduction of the palladium at the beginning of the catalyst bed due to the high temperature achieved by total oxidation of methane.

AB - Pd/Al2O3 catalysts oscillate between ignition and extinction of the catalytic partial oxidation of methane when they are exposed to a 2:1 reaction mixture of methane and oxygen. The oscillations of the catalytic performance and the structure of Pd/Al2O3 catalysts in a fixed-bed reactor were investigated using spatially and time-resolved in situ quick scanning X-ray absorption spectroscopy with online mass spectrometry. The dynamic methane conversion oscillated between an inactive state, where only combustion occurred, and an active state, after ignition, where partial oxidation of methane as a combination of total oxidation and reforming in the catalytic capillary reactor was observed. This change in catalytic performance was directly linked to changes in the oxidation state of the Pd/Al2O3 catalysts at different positions along the catalytic reactor. During the ignition of the catalytic partial oxidation of methane, the catalyst reduced from the end to the beginning of the catalyst bed and oxidized again toward the end as soon as the entire catalyst bed was reduced. On an entirely oxidized catalyst bed, only total oxidation of methane was observed and consumed the oxygen until the conditions at the end of the catalyst bed lead to a reduction of the catalyst bed again and a new cycle began with partial oxidation. Prior to the oxidation of the catalyst, a temporary lattice expansion appeared, which could be assigned to carbon intercalation into the palladium lattice. Furthermore, a sintering of the Pd particles at increasing age of the catalyst was observed, which leads to a lower oscillation frequency. Effects of particle size, oven temperature, and oxygen/methane ratio on the oscillation behavior were studied in detail. The deactivation period (reoxidation of Pd) was much less influenced by the oven temperature than the ignition behavior of the catalytic partial oxidation of methane. This indicates that deactivation is caused by an autoreduction of the palladium at the beginning of the catalyst bed due to the high temperature achieved by total oxidation of methane.

UR - http://pubs.acs.org/doi/full/10.1021/jp2052294

U2 - 10.1021/jp2052294

DO - 10.1021/jp2052294

JO - Journal of Physical Chemistry Part C: Nanomaterials and Interfaces

JF - Journal of Physical Chemistry Part C: Nanomaterials and Interfaces

SN - 1932-7447

IS - 1

VL - 116

SP - 599

EP - 609

ER -