CO Oxidation over Supported Gold Catalysts—“Inert” and “Active” Support Materials and Their Role for the Oxygen Supply during Reaction

Schubert, Markus M.; Hackenberg, Stefan; Veen, A.C. van; Mühler, Martin; Plzak, V.; Behm, R. Jürgen

doi:10.1006/jcat.2000.3069

Cited by 1,132 publications

(945 citation statements)

References 41 publications

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“…The presence of gold as small particles appear to be crucial for the high-activity [6,7]. Previous comparative studies showed that the activity of supported gold catalysts depends sensitively on the support materials [8][9][10]. Gold catalysts on a single oxide support were extensively studied.…”

Section: Introductionmentioning

confidence: 99%

“…However, Al 2 O 3 is not regarded as a good support for gold catalysts. Schubert et al's studies [8] showed that Al 2 O 3 was very different from reducible oxides such as FeO x , NiO x , CoO x and so on. When gold supported on the former oxide, which is believed to behave as neutral in the reaction process, only moderately active catalysts obtained.…”

Section: Introductionmentioning

confidence: 99%

“…However, Au catalysts supported on reducible transition metal oxides exhibited very high activities. Perhaps, this resulted from synergistic effects between the gold nanoparticles and support material [2,8,10,14,15]. Therefore, gold catalysts supported on composite MO x /Al 2 O 3 supports seem to have the possibility to realize the commercialization of high-activity catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Influence of pretreatment conditions on low-temperature CO oxidation over Au/MOx/Al2O3 catalysts

Wang

Hao

Cheng³

et al. 2003

Journal of Molecular Catalysis A: Chemical

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Composite oxide MO x /Al 2 O 3 supported gold catalysts for low-temperature CO oxidation were prepared and investigated. The presence of transition metal oxide was proved to be beneficial to the improvement of catalytic performance of Au/Al 2 O 3 catalysts for low-temperature CO oxidation. Furthermore, the influence of various pretreatment conditions on Au/MO x /Al 2 O 3 catalysts was studied carefully. The image of TEM showed that gold catalyst with small gold particles only in the form of a fine dispersion exhibited highly catalytic activity. The XPS, Fourier transform infrared (FTIR) spectroscopy characterization results of Au/FeO x /Al 2 O 3 catalyst showed that gold catalysts having partially oxidized gold species have the best catalytic performance. One possible pathway for CO oxidation on Au/FeO x /Al 2 O 3 catalyst is that the CO adsorbed on gold particles reacts with adsorbed oxygen, which is possible to occur on oxygen vacancies on the support or at the metal-support interface.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of pretreatment conditions on low-temperature CO oxidation over Au/MOx/Al2O3 catalysts

Wang

Hao

Cheng³

et al. 2003

Journal of Molecular Catalysis A: Chemical

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“…These observations indicate that the proposed gold-only activation mechanism of O 2 is unlikely under these reaction conditions. 8,13,15,16,19 With the help of X-ray irradiation, however, both surfaces can be effectively oxidized under 1 Torr of O 2 . Therefore, our observations demonstrate that X-rays play a critical dual role during in situ measurements and that extreme care must be taken to carry out experiments and interpret spectra, especially when using intense synchrotron radiation.…”

mentioning

confidence: 99%

Room-Temperature Reaction of Oxygen with Gold: An In situ Ambient-Pressure X-ray Photoelectron Spectroscopy Investigation

et al. 2010

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“…The enhanced catalytic activity of small gold clusters has been ascribed to a number of effects: bilayer structures that exhibit metal-nonmetal transitions [1][2][3], the metal-support interface [4][5][6][7], uncoordinated step-and corner atoms [8][9][10][11], strain [11], charge transfer from the support [12,13], and metal cationic sites [14]. Early work on model Au clusters supported on TiO 2 (110) correlated the presence of Au bilayer cluster morphologies (figure 1) with catalytic activity for CO oxidation [1].…”

mentioning

confidence: 99%

?Catalytically active Au on Titania:? yet another example of a strong metal support interaction (SMSI)?

2005

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In light of the many similarities between previous studies of the so-called strong metal support interaction (SMSI) involving Gr. VIII metals, and catalytically active Au, it is apparent that these two phenomena must be closely related. That active Au on titania spreads to form a bilayer structure, is electron-rich as determined by theory and experiment, nucleates on reduced Ti defects created by annealing to temperatures >750 K, and is deactivated via sintering in oxygen, is convincing evidence that the same basic principles responsible for activation of Au on titania are operative for SMSI involving Gr. VIII metals.KEY WORDS: gold, titania, CO oxidation, strong metal support interaction, SMSI.The enhanced catalytic activity of small gold clusters has been ascribed to a number of effects: bilayer structures that exhibit metal-nonmetal transitions [1][2][3], the metal-support interface [4][5][6][7], uncoordinated step-and corner atoms [8][9][10][11], strain [11], charge transfer from the support [12,13], and metal cationic sites [14]. Early work on model Au clusters supported on TiO 2 (110) correlated the presence of Au bilayer cluster morphologies (figure 1) with catalytic activity for CO oxidation [1]. These bilayer Au structures have been shown to bind CO approximately 50% more strongly than bulk Au (figure 2) [15]. Furthermore oxygen either alone or in a reaction mixture has been shown to promote sintering of these bilayer Au structures (figure 3) [1]. A recent model study [16] of Au on a highly reduced TiO x ordered film grown on Mo(112) has demonstrated that a coordinatively unsaturated, continuous Au bilayer structure that precludes assess of the reactant to the support, exhibits an exceptional high activity for catalytic CO oxidation (figure 4). The activity of this Au bilayer film is more than an order of magnitude more active than any previous report on a per Au atom basis [16]. A key feature of Au grown on TiO x /Mo(112) is the strength of the interaction between the overlayer Au and the support comprised of strong bonding between Au and reduced Ti atoms of the TiO x support, yielding electron-rich Au [16]. These recent studies are entirely consistent with recent theoretical studies [17] that show the importance of reduced Ti defect sites at the boundary between Au clusters and a TiO 2 interface in determining the Au cluster shape and electronic properties via transfer of charge from the support to Au [18]. Finally a recent theoretical study [19] has shown that a Au-only reaction pathway for a TiO x supported Au bilayer cluster is energetically competitive with alternative pathways requiring reactant-support interactions.In summary the essential features of the interaction of Au with TiO 2 that lead to enhanced catalytic activity are: (1) wetting of the support by the cluster; (2) strong bonding between the Au atoms at the interface with surface defects (reduced Ti sites); (3) electron-rich Au; (4) annealing at temperatures in excess of 750 K, sufficient to create and mobilize surface and bulk defects...

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CO Oxidation over Supported Gold Catalysts—“Inert” and “Active” Support Materials and Their Role for the Oxygen Supply during Reaction

Cited by 1,132 publications

References 41 publications

Influence of pretreatment conditions on low-temperature CO oxidation over Au/MOx/Al2O3 catalysts

Influence of pretreatment conditions on low-temperature CO oxidation over Au/MOx/Al2O3 catalysts

Room-Temperature Reaction of Oxygen with Gold: An In situ Ambient-Pressure X-ray Photoelectron Spectroscopy Investigation

?Catalytically active Au on Titania:? yet another example of a strong metal support interaction (SMSI)?

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