Turnover Rate and Reaction Orders for the Complete Oxidation of Methane on a Palladium Foil in Excess Dioxygen

Monteiro, Robson S.; Zemlyanov, Dmitry; Storey, John; Ribeiro, Fabio H.

doi:10.1006/jcat.2001.3176

Cited by 103 publications

(99 citation statements)

References 52 publications

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“…This could be related to a constant number of active sites, which would involve subsurface oxygen atoms participating into the reaction. Similar ideas were developed by Monteiro et al [16,17] in the study of Pd foils properties in the complete oxidation of methane. The surface measured by O 2 isotopic exchange was shown twice larger than the geometric surface of the Pd foil.…”

Section: Discussionmentioning

confidence: 64%

Oxidation behaviour and catalytic properties of Pd/Al2O3 catalysts in the total oxidation of methane

et al. 2006

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Section: Discussionmentioning

confidence: 64%

Oxidation behaviour and catalytic properties of Pd/Al2O3 catalysts in the total oxidation of methane

et al. 2006

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“…The Pd/6La-Al 2 O 3 , Pd/12 CeAl 2 O 3 and Pd/12La-Al 2 O 3 samples show a peak of Pd 3d and Pd 3p 3/2 at about 336.7 ± 1 eV and 534.3 ± 2 eV, respectively. The peak position is characteristic of PdO according to the literature [18,19]. Although Pd/Al 2 O 3 and Pd/6Ce-Al 2 O 3 samples shown a peak of Pd 3d at about 336.7 ± 1 eV, characteristic of PdO, the peak of Pd 3p 3/2 /O 1s is at 531.2 ± 2 eV and highly symmetric.…”

Section: Resultsmentioning

confidence: 96%

Effect of CeO2 and La2O3 on the Activity of CeO2−La2O3/Al2O3-Supported Pd Catalysts for Steam Reforming of Methane

et al. 2007

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The effect of the addition of CeO 2 or La 2 O 3 on the surface properties and catalytic behaviors of Al 2 O 3 -supported Pd catalysts was studied in the steam reforming of methane. The FTIR spectroscopy of adsorbed CO and the Pd dispersion suggest the partial coverage of Pd 0 by ceria or lanthana species. This could lead to the formation of an adduct MPd x O (M = Ce or La) at the surface of the metal crystallites. The addition of ceria or lanthana resulted in an increase of the turnover rate and specific rate for steam reforming of methane. One possible explanation if that the Pd 0 *Pd d+ O-M interfacial species (M = Ce or La) are oxidized by H 2 O or CO 2 , promoting the O* transfer to the metal surface. This could facilitate the removal of C* species from the metal surface, resulting in the increase of specific reaction rate and increase of the accessibility of CH 4 to metal active sites.

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“…The changes in the temperature region from 658 K to 778 K can be interpreted in terms of the formation of the bulk oxide phase PdO. Indeed, the position of the Pd 3d 5/2 peak at 336.56 eV is characteristic for bulk PdO [10][11][12][13][14][15][16]. The steep decrease of the O(II) coverage at the temperatures above 765 K corresponds to PdO decomposition.…”

Section: 1in-situ Xps: Heating In Oxygenmentioning

confidence: 99%

In situ XPS study of Pd(111) oxidation at elevated pressure, Part 2: Palladium oxidation in the 10−1mbar range

et al. 2006

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The oxidation of the Pd(111) surface was studied by in situ XPS during heating and cooling in 0.4 mbar O 2 . The in situ XPS data were complemented by ex situ TPD results. A number of oxygen species and oxidation states of palladium were observed in situ and ex situ. At 430 K, the Pd(111) surface was covered by a 2D oxide and by a supersaturated O ads layer. The supersaturated O ads layer transforms into the Pd 5 O 4 phase upon heating and disappears completely at approximately 470 K. Simultaneously, small clusters of PdO, PdO seeds, are formed. Above 655 K, the bulk PdO phase appears and this phase decomposes completely at 815 K. Decomposition of the bulk oxide is followed by oxygen dissolution in the near-surface region and in the bulk. The oxygen species dissolved in the bulk is more favoured at high temperatures because oxygen cannot accumulate in the near-surface region and diffusion shifts the equilibrium towards the bulk species. The saturation of the bulk "reservoir" with oxygen leads to increasing the uptake of the near-surface region species. Surprisingly, the bulk PdO phase does not form during cooling in 0.4 mbar O 2 , but the Pd 5 O 4 phase appears below 745 K. This is proposed to be due to a kinetic limitation of PdO formation because at high temperature the rate of PdO seed formation is compatible with the rate of decomposition.

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Turnover Rate and Reaction Orders for the Complete Oxidation of Methane on a Palladium Foil in Excess Dioxygen

Cited by 103 publications

References 52 publications

Oxidation behaviour and catalytic properties of Pd/Al2O3 catalysts in the total oxidation of methane

Oxidation behaviour and catalytic properties of Pd/Al2O3 catalysts in the total oxidation of methane

Effect of CeO2 and La2O3 on the Activity of CeO2−La2O3/Al2O3-Supported Pd Catalysts for Steam Reforming of Methane

In situ XPS study of Pd(111) oxidation at elevated pressure, Part 2: Palladium oxidation in the 10−1mbar range

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