Gold–ceria catalysts for low-temperature water-gas shift reaction

Fu, Qi; Kudriavtseva, Svetlana; Saltsburg, Howard; Flytzani‐Stephanopoulos, Maria

doi:10.1016/s1385-8947(02)00107-9

Cited by 470 publications

(490 citation statements)

References 39 publications

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“…Another way to state this is that the number of active sites for CO oxidation on the gold clusters of the pre-reduced sample is higher than on the gold particles of the parent. The activity of the reduced 0.7AuFe 2 O 3 catalyst is comparable to the most active CO oxidation catalysts Au/TiO 2 [4] and Au/Fe(OH) 3 [50] reported in the literature (table 1) which were tested in a gas mixture composed of 1%CO and 20%O 2 .…”

Section: Co Oxidation On Au/fe 2 Osupporting

confidence: 69%

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Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

et al. 2007

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We compare the activity and relevant gold species of nanostructured gold-cerium oxide and gold-iron oxide catalysts for the CO oxidation by dioxygen and water. Well dispersed gold nanoparticles in reduced form provide the active sites for the CO oxidation reaction on both oxide supports. On the other hand, oxidized gold species, strongly bound on the support catalyze the water-gas shift reaction. Gold species weakly bound to ceria (doped with lanthana) or iron oxide can be removed by sodium cyanide at pH ‡12. Both parent and leached catalysts were investigated. The activity of the leached gold-iron oxide catalyst in CO oxidation is approximately two orders of magnitude lower than that of the parent material. However, after exposure to H 2 up to 400°C gold diffuses out and is in reduced form on the surface, a process accompanied by a dramatic enhancement of the CO oxidation activity. Similar results were found with the gold-ceria catalysts. On the other hand, pre-reduction of the calcined leached catalyst samples did not promote their water-gas shift activity. UV-Vis, XANES and XPS were used to probe the oxidation state of the catalysts after various treatments.

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Section: Co Oxidation On Au/fe 2 Osupporting

confidence: 69%

“…It has been reported that formation of reactive oxygen species on nanocrystalline ceria is enhanced by the presence of gold [27,50]. Gold on nanoscale ceria is two orders of magnitude more active for the CO oxidation reaction than if deposited on microcrystalline ceria [11].…”

Section: Co Oxidation On Au/ceomentioning

confidence: 99%

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

et al. 2007

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“…Interestingly, this observation is in contrast to reports of Au/CeO 2 , in which Au NPs only affected the reduction surface ceria species, but not the bulk. 34,35 In the presence of Au NPs, the WO 3 species were generally more reducible than without Au NPs, as shown by the shifting of reduction events to lower temperatures. Complete reduction to W 0 was shown at temperatures below 1000 °C for Auloaded catalysts, but SiO 2 -WO 3 and WO 3 were not completely reduced up to 1000 °C.…”

Section: Resultsmentioning

confidence: 99%

“…The extent of this effect depends on the preparation method of the Au-oxide catalyst and the concentration of nanoparticles within the oxide. 33,34 In this study, we sought to explore the reducibility of WO 3 with Au NPs, using the transformation of MeOH as a probe reaction. This reaction serves as a good catalytic characterization tool to better understand acid and redox catalysts.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Influence of Au Nanoparticles on Porous SiO₂–WO₃ and WO₃ Methanol Transformation Catalysts

et al. 2016

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American Chemical SocietyDepuccio, DP.; Ruiz-Rodríguez, L.; Rodriguez-Castellon, E.; Botella Asuncion, P.; López Nieto, JM.; Landry, CC. (2016) AbstractAnalyzing the structural and chemical properties of materials at the interface of metal nanoparticles and metal oxide supports is important for catalytic applications. Tungsten oxide (WO 3 ) is a widely studied catalyst, but changing the catalytic reactivity at the surface of this oxide with metal nanoparticles is of interest. In this work, we sought to modify the redox properties of porous WO 3 and SiO 2 -WO 3 catalysts with sonochemically deposited gold nanoparticles (Au NPs) in order to access and study this reaction pathway. Characterization using powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and inductively-coupled plasma optical emission spectroscopy (ICP-OES) confirmed that crystalline Au NPs with diameters of 5 -12 nm were distributed throughout the catalysts. Temperature-programmed desorption (TPD) was used to probe the surface acidity of the catalysts. The physic-chemical characteristics of catalysts have been also discussed by considering the catalytic performance of these materials in the aerobic transformation of methanol. Catalysts containing nanocrystalline WO 3 but no Au NPs displayed very high selectivity to DME (> 60%) at all conversions with minor oxidation reactivity, which highlighted the acidic nature of these catalysts. No effect on the acidity of the catalysts was observed by TPD when Au NPs were loaded in the catalysts. The reducibility of the crystalline WO 3 species, however, increased significantly due to the interaction with Au NPs, as observed by temperature-programmed reduction (TPR). In the gas-phase transformation of MeOH under aerobic conditions, catalysts modified with Au NPs showed greater activity compared to non-modified catalysts. In addition, oxidation selectivity to products such as methyl formate as well as formaldehyde, dimethoxymethane, and carbon oxides became heavily favored with only minor dehydration selectivity. The redox properties of these WO 3 catalysts could be tuned by changing the Au loading. More labile lattice oxygen and enhanced redox properties at the surface of WO 3 modified with Au NPs clearly altered these traditional dehydration catalysts to potential oxidation catalysts. Thus, modification of WO 3 with Au is an effective way to expand the MeOH transformation product distribution beyond DME to other useful, oxidized products not typically observed over pure WO 3 .

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“…The rationale behind the use of these materials in this reaction is related to the oxygen storage capacity of the catalysts. CeO 2 can desorb and re-adsorb O 2 through formation and consumption of a Ce 2 O 3 oxide [16][17][18][19][20]. The oxygen atoms involved in this process are active for promotion of various combustion and reforming reactions [21][22][23][24][25] and for this reason (as well as their ability to dampen excursions to overly fuel rich or fuel lean exhaust conditions) Ce (x) Zr (1-x) O 2 catalysts are used as supports in many catalytic formulations.…”

Section: Introductionmentioning

confidence: 99%

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

Sullivan

Dulgheru

Atribak

et al. 2011

Applied Catalysis B: Environmental

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Publisher's statementThis is the author's version of a work that was accepted for publication in Applied Catalysis B: Environmental. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Catalysis B: Environmental, 108-109 (1) Ce (x) Zr (1-x) O 2 catalysts with various Ce / Zr contents were studied using Raman spectroscopy under different gaseous atmospheres, at different temperatures and in the presence of a model soot.Catalysts with high concentrations of Zr fluoresced at elevated temperatures making analysis of their spectra impossible. This effect became even more pronounced at higher temperatures. CeO 2 and solid solutions with relatively low concentrations of Zr showed a red shift and a decrease in intensity of the characteristic F 2g peak at high temperatures under different atmospheres. The magnitude of the latter effect was higher under reducing atmospheres. These changes are reversible upon cooling, showing that they relate to a lattice expansion effect rather than any major chemical change to the material. In the presence of the model soot the Raman spectra of all materials was much decreased due to the absorption of the incident and scattered radiation by the soot particles. The presence of soot does not change the relative intensities or positions of the peaks in the spectra of the solid solutions. Evidence is shown for the production of a Ce 3+ -CO species following interaction between the soot and the surface at high temperature in an inert atmosphere.

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Gold–ceria catalysts for low-temperature water-gas shift reaction

Cited by 470 publications

References 39 publications

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

Investigating the Influence of Au Nanoparticles on Porous SiO₂–WO₃ and WO₃ Methanol Transformation Catalysts

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

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Gold–ceria catalysts for low-temperature water-gas shift reaction

Cited by 470 publications

References 39 publications

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

Comparison of the activity of Au/CeO2 and Au/Fe2O3 catalysts for the CO oxidation and the water-gas shift reactions

Investigating the Influence of Au Nanoparticles on Porous SiO2–WO3 and WO3 Methanol Transformation Catalysts

Attempts at an in situ Raman study of ceria/zirconia catalysts in PM combustion

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Investigating the Influence of Au Nanoparticles on Porous SiO₂–WO₃ and WO₃ Methanol Transformation Catalysts