Selective oxidation of propylene over gold deposited on titanium-based oxides

Haruta, Masatake; Uphade, Balu S.; Tsubota, Susumu; Miyamoto, Akira

doi:10.1163/156856798x00276

Cited by 182 publications

(128 citation statements)

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“…In Fig. 31, the relationship between Au and Ti cations for the rutile and anatase forms of titania are depicted, revealing the differences in spacing between Ti and Au (522). As discussed in Molina and Hammer's work with CO oxidation (474), the transition state is probably rather complex therefore very precise interatomic distances are required (523).…”

Section: Figure 29mentioning

confidence: 89%

“…TiO2-SiO2 mesoporous crystalline structures have proven to be active for this reaction (425,519,520,523,524) as well when possessing the proper Ti:Si ratio (generally below 3:100) (524,525). It is speculated that this may be related to a steric effect whereby Ti cations must be spaced at critical distances (522,523) as catalysts with such mesoporous material supports tend to be less active with increasing Au and Ti content (525). In Fig.…”

Section: Figure 29mentioning

confidence: 98%

“…The choice of support is of critical importance for selective oxidation of propene as only anatase TiO2 supports and neither rutile nor amorphous TiO2 supports have shown to be active (522). TiO2-SiO2 mesoporous crystalline structures have proven to be active for this reaction (425,519,520,523,524) as well when possessing the proper Ti:Si ratio (generally below 3:100) (524,525).…”

Section: Figure 29mentioning

confidence: 99%

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Surface chemistry of catalysis by gold

et al. 2004

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IntroductionGold has long been regarded as an "inert" surface and bulk gold surfaces do not chemisorb many molecules easily. However, in the last decade, largely through the efforts of Masatake Haruta, gold particles, particularly those below 5 nm in size, have begun to garner attention for unique catalytic properties (1-8). In recent years, supported gold particles have been shown to be effective as catalysts for low temperature CO oxidation (9), selective oxidation of propene to propene oxide (10), water gas shift (11), NO reduction (12), selective hydrogenation of acetylene (or butadiene) (13)

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Section: Figure 29mentioning

confidence: 89%

Section: Figure 29mentioning

confidence: 98%

Section: Figure 29mentioning

confidence: 99%

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Surface chemistry of catalysis by gold

et al. 2004

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“…In Figure 9 the distribution of AuNPs on different mesoporous SiO 2 -based supports is depicted, while some synthesis procedures and catalytic applications are briefly discussed below. In the late of 90s, the Haruta's group initiated the investigation of the catalytic activity of gold deposited on titanium-containing mesoporous MCM-41 and MCM-48 materials, for the partial oxidation of propylene to propylene oxide, in the presence of oxygen and hydrogen [188][189][190][191][192][193][194][218][219][220][221][222][223]. They prepared Ti-doped MCM-41 and MCM-48 by means of a sol-gel process using tetrabutylorthotitanate [Ti(OC 4 H 9 ) 4 ] as titanium source, and then gold (4-12%wt) was loaded on these supports by DP (T = 70 °C, pH = 6.5-7.0) or by liquid grafting methods using HAuCl 4 or (CH 3 ) 2 Au(O 2 C 5 H 7 ) as gold precursors, respectively.…”

Section: Sio 2 -Based Gold Catalystsmentioning

confidence: 99%

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

2011

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Mesoporous silica materials (MSM) with ordered and controllable porous structure, high surface area, pore volume and thermal stability are very suitable catalyst supports, because they provide high dispersion of metal nanoparticles and facilitate the access of the substrates to the active sites. Since the conventional wet-impregnation and deposition-precipitation methods are not appropriate for the incorporation of gold nanoparticles (AuNPs) into MSM, considerable efforts have been made to develop suitable methods to synthesize Au/MSM catalysts, because the incorporation of AuNPs into the channel system can prevent their agglomeration and leaching. In this review, we summarize the main methods to synthesize active gold catalysts supported on MSM. Examples and details of the preparative methods, as well as selected applications are provided. We expect this article to be interesting to researchers due to the wide variety of chemical reactions that can be catalyzed by gold supported catalysts.

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“…A short while ago it was discovered that, unlike bulk gold, small gold clusters are chemically active and are promising catalysts for partial oxidation [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and partial hydrogenation [15][16][17] reactions. We are particularly interested in Haruta's discovery 1 that Au clusters, supported on TiO 2 , epoxidize propene with very high selectivity.…”

Section: Introductionmentioning

confidence: 99%

Binding of propene on small gold clusters and on Au(111): Simple rules for binding sites and relative binding energies

Chrétien

Gordon

Metiu

2004

The Journal of Chemical Physics

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We use density functional theory(DFT) to investigate the bonding of propene to small gas-phase gold clusters and to a Au(111) surface. The desorption energy trends and the geometry of the binding sites are consistent with the following set of rules.(1) The bond of propene to gold is formed by donation of electron density from the highest occupied molecular orbital (HOMO) of propene to one of the low-lying empty orbitals [denoted by LUMO1, LUMO2, … (LUMO-lowest unoccupied molecular orbital)] of the gold cluster. (2) Propene binds to a site on the Au cluster where one of the low-lying LUMOs protrudes in the vacuum. Different isomers (same cluster, but different binding sites for propene) correspond to sites where different low-lying LUMOs protrude in space. (3) The desorption energy of the lowest energy isomer correlates with the energy of the lowest empty orbital of the cluster; the lower the energy of that LUMO, the higher the desorption energy. (4) If the lowest-lying LUMO protrudes into space at two nonequivalent sites at the edge of a cluster, propene binds more strongly to the site with the lowest coordination. These rules are consistent with the calculated bond energies and geometries for [Aun(C3H6)]q, for n=1−5 and n=8 and q=−1, 0, +1. Based on them we have made a number of predictions that have been confirmed by DFT calculations. The bond of propene to gold is strengthened as the net charge of the cluster varies from −1, to zero, to +1. Compared to a gas-phase cluster, a cluster on a support binds propene more strongly if the support takes electron density from the cluster (e.g., a Au cluster on a goldsurface) and more weakly if the support donates electron density to the cluster (e.g., a Au cluster on an oxygen vacancy on an oxide surface). KeywordsGold, Binding sites, Density functional theory, Desorption, Oxide surfaces Disciplines Chemistry CommentsThe following article appeared in Journal of Chemical Physics 121 (2004) We use density functional theory ͑DFT͒ to investigate the bonding of propene to small gas-phase gold clusters and to a Au͑111͒ surface. The desorption energy trends and the geometry of the binding sites are consistent with the following set of rules. ͑1͒ The bond of propene to gold is formed by donation of electron density from the highest occupied molecular orbital ͑HOMO͒ of propene to one of the low-lying empty orbitals ͓denoted by LUMO1, LUMO2, ... ͑LUMO-lowest unoccupied molecular orbital͔͒ of the gold cluster. ͑2͒ Propene binds to a site on the Au cluster where one of the low-lying LUMOs protrudes in the vacuum. Different isomers ͑same cluster, but different binding sites for propene͒ correspond to sites where different low-lying LUMOs protrude in space. ͑3͒ The desorption energy of the lowest energy isomer correlates with the energy of the lowest empty orbital of the cluster; the lower the energy of that LUMO, the higher the desorption energy. ͑4͒ If the lowest-lying LUMO protrudes into space at two nonequivalent sites at the edge of a cluster, propene binds more strong...

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Selective oxidation of propylene over gold deposited on titanium-based oxides

Cited by 182 publications

References 5 publications

Surface chemistry of catalysis by gold

Surface chemistry of catalysis by gold

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

Binding of propene on small gold clusters and on Au(111): Simple rules for binding sites and relative binding energies

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