In-situ XPS Study on the Reducibility of Pd-Promoted Cu/CeO2 Catalysts for the Oxygen-assisted Water-gas-shift Reaction

Fox, Elise B.; Lee, Adam F.; Wilson, Karen; Song, Chunshan

doi:10.1007/s11244-008-9063-6

Cited by 48 publications

(27 citation statements)

References 38 publications

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“…Figure 3a shows the Pd 3d spectra that characterize the changes in the palladium particles supported on aluminum oxide as a result of the interaction of the Pd/Al 2 O 3 model sample with NO x at room tempera ture. The Pd : Al atomic ratio in the initial sample was [23][24][25][26][27]. For the initial sample, the peaks in the Pd 3d doublet have an asymmetric shape typical of the metallic state, and the I as : I sym ratio is 1.46.…”

Section: Resultsmentioning

confidence: 99%

An XPS study of the oxidation of noble metal particles evaporated onto the surface of an oxide support in their reaction with NO x

et al. 2012

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The interaction of the model catalysts with NO x (mixture of 10 Torr of NO and 10 Torr of O 2 ) was studied by X ray photoelectron spectroscopy (XPS). Sam ples of the model catalysts were prepared under vacuum conditions as oxide films ≥100 Å in thickness on tan talum foil with evaporated platinum group metal particles. According to transmission electron microscopic data, the platinum group metal particle size was several nanometers. It was found by XPS that the oxidation of Rh and Pd nanoparticles in their interaction with NO x occurs already at room temperature. The particles of platinum were more stable: their oxidation under the action of NO x was observed at elevated temperatures of ~300°C. At room temperature, the interaction of platinum nanoparticles with NO x hypothetically leads to the dissolution (insertion) of oxygen atoms in the bulk of the particles with the retention of their metallic nature. It was found that dissolved oxygen is much more readily reducible by hydrogen than the lattice oxygen of the platinum oxide particles.

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Section: Resultsmentioning

confidence: 99%

An XPS study of the oxidation of noble metal particles evaporated onto the surface of an oxide support in their reaction with NO x

et al. 2012

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“…The obtained nanoparticles were loaded on common oxide supports. In situ X-ray photoelectron spectroscopy (XPS) [37][38][39][40][41] and high-sensitivity low-energy ion scattering spectroscopy (HS-LEIS) [42][43][44] were used to characterize the chemical states and compositions after different treatments. Phase diagrams of the surface composition as a function of the bulk composition were obtained and compared with those of unsupported PtCu alloy nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

The effect of the support on the surface composition of PtCu alloy nanocatalysts: In situ XPS and HS-LEIS studies

Huang

Song

et al. 2017

Chinese Journal of Catalysis

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Supported PtCu alloys have been broadly applied in heterogeneous catalysis and electrocatalysis owing to their excellent catalytic performance and high CO tolerance. It is important to analyze the outermost surface composition of the supported alloy nanoparticles to understand the nature of the catalytically active sites. In this paper, homogeneous face-centered cubic PtCu nanoparticles with a narrow particle size distribution were successfully fabricated and dispersed on a high-surface-area TiO2 powder support. The samples were oxidized and reduced in situ and then introduced into the ultrahigh vacuum chamber to measure the topmost surface composition by high-sensitivity low-energy ion scattering spectroscopy, and to determine the oxidation states of the elements by X-ray photoelectron spectroscopy. The surface composition and morphology, elemental distribution, and oxidation states of the components were found to be significantly affected by the support and treatment conditions. The PtCu is de-alloyed upon oxidation with CuO wetting on the TiO2 surface and re-alloyed upon reduction. Phase diagrams of the surface composition and the bulk composition were plotted and compared for the supported and unsupported materials.

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“…Table 2 shows the surface concentrations and binding energies of catalysts 3 (Ce-Bi-O), 9 (Ce-Pt-O), and 8 (Ce-Bi-Pt-O), as determined by XPS. [49] The surface concentrations of the dopants are lower than the expected bulk value (see Table 2). However, the surface concentration ratios of Bi and Pt of the three catalysts are in accordance with the bulk concentrations.…”

Section: Addition Of Platinummentioning

confidence: 85%

Bismuth‐Doped Ceria, Ce_0.90Bi_0.10O₂: A Selective and Stable Catalyst for Clean Hydrogen Combustion

Beckers¹,

Lee²,

Rothenberg³

2009

Adv Synth Catal

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Bismuth-doped cerias are successfully applied as solid "oxygen reservoirs" in the oxidative dehydrogenation of propane. The lattice oxygen of the ceria is used to selectively combust hydrogen from the dehydrogenation mixture at 550 8C. This process has three key advantages: it shifts the dehydrogenation equilibrium to the desired products side, generates heat, aiding the endothermic dehydrogenation, and simplifies product separation (water vs. hydrogen). Furthermore, the process is safer, since it uses the catalysts lattice oxygen instead of gaseous oxygen. We show here that bismuth-doped cerias are highly active and stable towards hydrogen combustion, and explore four different approaches for optimising their application in the oxidative dehydrogenation of propane: first, the addition of extra hydrogen which lowers hydrocarbon conversion by suppressing both combustion and coking; second, the addition of tin which completely inhibits coking; third, the addition of platinum which increases selectivity, but at the expense of lower activity. The best results are obtained through tuning the reaction temperature. At 400 8C, high activity and selectivity were obtained for the bismuth-doped ceria Ce 0.90 Bi 0.10 O 2 . Here, 90% of the hydrogen feed is converted at 98% selectivity. This optimal reaction temperature can be rationalised from the hydrogen and propene temperature-programmed reduction (TPR) profiles: 400 8C lies above the reduction maximum of hydrogen, yet below that of propene. That is, this temperature is sufficiently high to facilitate rapid hydrogen combustion, but low enough to prevent hydrocarbon conversion.

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In-situ XPS Study on the Reducibility of Pd-Promoted Cu/CeO2 Catalysts for the Oxygen-assisted Water-gas-shift Reaction

Cited by 48 publications

References 38 publications

An XPS study of the oxidation of noble metal particles evaporated onto the surface of an oxide support in their reaction with NO x

An XPS study of the oxidation of noble metal particles evaporated onto the surface of an oxide support in their reaction with NO x

The effect of the support on the surface composition of PtCu alloy nanocatalysts: In situ XPS and HS-LEIS studies

Bismuth‐Doped Ceria, Ce_0.90Bi_0.10O₂: A Selective and Stable Catalyst for Clean Hydrogen Combustion

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In-situ XPS Study on the Reducibility of Pd-Promoted Cu/CeO2 Catalysts for the Oxygen-assisted Water-gas-shift Reaction

Cited by 48 publications

References 38 publications

An XPS study of the oxidation of noble metal particles evaporated onto the surface of an oxide support in their reaction with NO x

An XPS study of the oxidation of noble metal particles evaporated onto the surface of an oxide support in their reaction with NO x

The effect of the support on the surface composition of PtCu alloy nanocatalysts: In situ XPS and HS-LEIS studies

Bismuth‐Doped Ceria, Ce0.90Bi0.10O2: A Selective and Stable Catalyst for Clean Hydrogen Combustion

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Product

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Bismuth‐Doped Ceria, Ce_0.90Bi_0.10O₂: A Selective and Stable Catalyst for Clean Hydrogen Combustion