Low-temperature water-gas shift reaction over Au/CeO2 catalysts

Andreeva, D.; Idakiev, V.; Tabakova, T.; Ilieva, L.; Falaras, Polycarpos; Bourlinos, Athanasios B.; Travlos, A.

doi:10.1016/s0920-5861(01)00477-1

Cited by 420 publications

(231 citation statements)

References 11 publications

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“…Au 0 reduction and is in line with published data (T max = 375-500 K) for ceria supported Au involving a range of syntheses [21]. Hydrogen consumption during TPR 12 mol H 2 mol À1 Au À Á was eight times greater than that required for reduction to metallic gold, indicative of partial support reduction with the formation of surface oxygen vacancies [22]. STEM analysis (Fig.…”

Section: Resultssupporting

confidence: 89%

Overcoming the limitations of gold catalysts in hydrogenation: enhanced activity with full hydrogen utilization

Keane

Collado

et al. 2018

Reac Kinet Mech Cat

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Application of nano-scale supported Au in catalytic hydrogenation delivers high chemoselectivity but low activity using (pressurized) H 2 far in excess of stoichiometric requirements. We have tackled the issues of low reaction rate and inefficient hydrogen utilization through a series of approaches taking Au/CeO 2 (mean Au size = 2.8 nm) as a test catalyst. Increased spillover hydrogen (using physical mixtures of Au/CeO 2 with CeO 2 and SiO 2 ) and the promotional effect of water (via catalytic dissociation on surface oxygen vacancies) resulted in a fourfold increase in the selective rate of furfural hydrogenation to furfuryl alcohol. In contrast, Pd/CeO 2 and Ni/CeO 2 promoted decarbonylation (to furan), hydrogenolysis (to 2-methylfuran) and ring reduction (to tetrahydrofurfuryl alcohol). Coupling (2-butanol ? 2-butanone) dehydrogenation over Cu/SiO 2 (mean Cu size = 7.8 nm) with furfural hydrogenation over Au/CeO 2 further increased rate with full utilization of the hydrogen generated in dehydrogenation. The coupling strategy allows ''hydrogen free'' hydrogenation that circumvents the limitation of Au in standard catalytic hydrogenation. This can open new avenues to exploit the ultra-selectivity of Au for continuous production of high value commodity products.

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Section: Resultssupporting

confidence: 89%

Overcoming the limitations of gold catalysts in hydrogenation: enhanced activity with full hydrogen utilization

Keane

Collado

et al. 2018

Reac Kinet Mech Cat

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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%

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 nature of the active species in highly dispersed Au catalysts (ionic vs metallic, low-coordinated surface atoms vs metal/support interface) is a matter of extensive debates. Among many gold catalysts reported in the literature, those supported on the cerium oxide (CeO 2 ) often show a superior activity ( [2][3][4][5][6][7][8][9], and references therein). It should be mentioned that the reaction mechanisms, involving cationic Au 3+ and Au + species as the most active, have been reinforced after experimental observations by Flutzani-Staphanopolus and co-workers on the Au/CeO 2 catalysts [10].…”

Section: Introductionmentioning

confidence: 99%

Gold supported on well-ordered ceria films: nucleation, growth and morphology in CO oxidation reaction

et al. 2007

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Abstract. Structure of gold nanoparticles formed by physical vapor deposition onto thin ceria films was studied by scanning tunneling microscopy (STM). Gold preferentially nucleates on point defects present on the terraces of the well-ordered, fully oxidized films to a low density. The nucleation expands to the terrace step edges, providing a large variety of low-coordinated sites. Only at high coverage, the Au particles grow homogeneously on the oxygen-terminated CeO 2 (111) terraces. The morphology of Au particles was further examined by STM in situ and ex situ at elevated (up to 20 mbar) pressures of O 2 , CO, and CO + O 2 at 300 K. The particles are found to be stable in O 2 ambient up to 10 mbar, meanwhile gold sintering emerges at CO pressures above ~ 1 mbar. Sintering of the Au particles, which mainly proceeds along the step edges of the CeO 2 (111) support, is observed in CO + O 2 (1:1) mixture at much lower pressure (~10 -3 mbar), thus indicating that the structural stability of the Au/ceria catalysts is intimately connected with its reactivity in the CO oxidation reaction.

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Low-temperature water-gas shift reaction over Au/CeO2 catalysts

Cited by 420 publications

References 11 publications

Overcoming the limitations of gold catalysts in hydrogenation: enhanced activity with full hydrogen utilization

Overcoming the limitations of gold catalysts in hydrogenation: enhanced activity with full hydrogen utilization

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

Gold supported on well-ordered ceria films: nucleation, growth and morphology in CO oxidation reaction

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Low-temperature water-gas shift reaction over Au/CeO2 catalysts

Cited by 420 publications

References 11 publications

Overcoming the limitations of gold catalysts in hydrogenation: enhanced activity with full hydrogen utilization

Overcoming the limitations of gold catalysts in hydrogenation: enhanced activity with full hydrogen utilization

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

Gold supported on well-ordered ceria films: nucleation, growth and morphology in CO oxidation reaction

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