Role of cationic gold in supported CO oxidation catalysts

Fierro-Gonzalez, Juan C.; Guzmán, Javier; Gates, Bruce C.

doi:10.1007/s11244-007-0283-y

Cited by 77 publications

(47 citation statements)

References 81 publications

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“…The dried Au/CeO 2 (rod) catalysts contain a whiteline at *4 eV above the edge, which is typical for Au 3? compounds [62]. This feature is more intense for the leached catalyst, indicating that a larger fraction of the gold atoms is in the cationic form.…”

Section: Resultsmentioning

confidence: 95%

“…After oxidation this band disappears. X-ray absorption spectroscopy is a useful technique to obtain detailed information about the oxidation state and structure of small supported gold particles [61][62][63][64][65]. Au L III near-edge spectra at room temperature, drying and reduction at various temperatures for Au/CeO 2 (rod), Au/ CeO 2 (rod)-CN and Au/CeO 2 (cube) are collected in Fig.…”

Section: Resultsmentioning

confidence: 99%

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Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

et al. 2011

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The interaction of gold atoms with CeO 2 nanocrystals having rod and cube shapes has been examined by cyanide leaching, TEM, TPR, CO IR and X-ray absorption spectroscopy. After deposition-precipitation and calcination of gold, these surfaces contain gold nanoparticles in the range 2-6 nm. For the ceria nanorods, a substantial amount of gold is present as cations that replace Ce ions in the surface as follows from their first and second coordination shells of oxygen and cerium by EXAFS analysis. These cations are stable against cyanide leaching in contrast to gold nanoparticles. Upon reduction the isolated Au atoms form finely dispersed metal clusters with a high activity in CO oxidation, the WGS reaction and 1,3-butadiene hydrogenation. By analogy with the very low activity of reduced gold nanoparticles on ceria nanocubes exposing the {100} surface plane, it is inferred that the gold nanoparticles on the ceria nanorod surface also have a low activity in such reactions. Although the finely dispersed Au clusters are thermally stable up to quite high temperature in line with earlier findings (Y. Guan and E. J. M. Hensen, Phys Chem Chem Phys 11:9578, 2009), the presence of gold nanoparticles results in their more facile agglomeration, especially in the presence of water (e.g., WGS conditions). For liquid phase alcohol oxidation, metallic gold nanoparticles are the active sites. In the absence of a base, the O-H bond cleavage appears to be rate limiting, while this shifts to C-H bond activation after addition of NaOH. In the latter case, the gold nanoparticles on the surface of ceria nanocubes are much more active than those on the surface of nanorod ceria.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

et al. 2011

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“…There are a large number of works discussing the active sites of supported gold catalysts in CO oxidation, the proposed reaction sites include cationic gold species [53,54], bilayer gold clusters composed of less than 10 atoms [55,56], and the junction perimeter between gold and the metal oxide support [57]. In the case of Au-Cu bimetallic catalysts, we did not detect any cationic gold species in either pretreated catalyst or working catalyst; only Au 0 was identified by both IR and XANES examinations.…”

Section: Active Sites In Co Oxidationmentioning

confidence: 99%

Structural changes of Au–Cu bimetallic catalysts in CO oxidation: In situ XRD, EPR, XANES, and FT-IR characterizations

Liu¹,

Wang²,

Li³

et al. 2011

Journal of Catalysis

263

165

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“…Our studies, which show cycling of the oxidation state of the Au particles during the decomposition of DMMP, have been used in conjunction with previous work to provide a description of the overall mechanism of oxidation. 11,[17][18][19][20][21][22] Details of the mechanism are discussed in detail in the publications listed in this final report. Briefly, we find that the activation of oxygen involves charge transfer from a Au δ+ site residing at the periphery of a Au particle to form an active oxygen species, probably O 2 -.…”

Section: Hrtem Of 22 Nm Particlesmentioning

confidence: 99%

Adsorption and Decomposition of CWA Simulants on Single Crystal and Nanostructured Metal Oxides

Morris¹

2009

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Tech Final Report I. ForewordOur studies are directed at determining the adsorption mechanisms and reaction pathways for the chemical warfare agent simulant (CWA) for GB (Sarin) on metal oxide surfaces and nanoparticles. By learning about how surface structure, nanoparticle size, composition, and surface co-adsorbates affect the overall interfacial chemistry, we are providing insight that can be applied toward the development of effective sorbent materials for protection and decontamination. Our approach couples ultrahigh vacuum (UHV) surface analysis instrumentation with precision simulant dosing capabilities to explore agent reactivity on highly characterized and contaminant-free metal oxide surfaces. Our work during this funding period has focused on studying the uptake and decomposition of the simulant dimethyl methylphosphonate (DMMP) when it impinges on the surface of nanoparticulate systems.

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Role of cationic gold in supported CO oxidation catalysts

Cited by 77 publications

References 81 publications

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

Gold Stabilized by Nanostructured Ceria Supports: Nature of the Active Sites and Catalytic Performance

Structural changes of Au–Cu bimetallic catalysts in CO oxidation: In situ XRD, EPR, XANES, and FT-IR characterizations

Adsorption and Decomposition of CWA Simulants on Single Crystal and Nanostructured Metal Oxides

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