Vapor-Phase Epoxidation of Propene Using H2 and O2 over Au/Ti–MCM-48

Uphade, Balu S.; Akita, Tomoki; Nakamura, T.; Haruta, Masatake

doi:10.1006/jcat.2002.3642

Cited by 224 publications

(164 citation statements)

References 34 publications

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“…Studies on gold supported catalysts have been mainly focused on gas-phase oxidation, such as CO oxidation [1][2][3][4], complete oxidation of hydrocarbons [5][6][7][8][9][10][11], selective oxidation [12][13][14][15][16][17][18][19][20], and water-gas shift (WGS) reaction [21][22][23][24]. Studies on the use of gold catalysts for the synthesis of fine chemicals in liquid phase have recently received much more attention.…”

Section: Introductionmentioning

confidence: 99%

Gold on titania: Effect of preparation method in the liquid phase oxidation

Dimitratos

Villa

Bianchi

et al. 2006

Applied Catalysis A: General

129

106

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The effect of preparation method (deposition-precipitation versus sol immobilisation method) and reduction method (calcination versus chemical reduction) on Au/TiO 2 catalysts for the liquid phase oxidation of glycerol has been studied. It was revealed that a different trend existed in terms of activity and distribution of products. The catalytic activity is shown to be dependent not only on the choice of the reduction method but also on the use of protective agent (PVA, THPC) for the stabilization of the gold colloids. In fact, the highest activity was found when a low temperature chemical reduction was employed on a Au/TiO 2 sample synthesised by the deposition-precipitation method. The use of a higher pre-treatment temperature or of a protective agent resulted in a lower activity but could be used to direct selectivity in oxidation reactions. The structural data (HRTEM and XPS) along with the catalytic results indicate that the combination of metallic Au 0 species with small particle size (2-5 nm) are responsible for the high activity observed in the liquid phase oxidation of glycerol. #

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Section: Introductionmentioning

confidence: 99%

Gold on titania: Effect of preparation method in the liquid phase oxidation

Dimitratos

Villa

Bianchi

et al. 2006

Applied Catalysis A: General

129

106

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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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“…In the early days, the support was introduced to merely disperse metal nanoparticles and was thought to be inert in the catalytic process, but in later research the support has been demonstrated in many cases for its signifi cant role in catalytic reactions [119,131,132] . Recent work by Sonstr ö m et al demonstrated that ligandcapped colloidal Pt nanoparticles, after deposition onto nanostructured iron oxide, can catalyze CO oxidation at unusually low temperatures [133] , similar to the Au-catalyzed CO oxidation by Haruta and coworkers [134].…”

Section: Metal-support Interactionsmentioning

confidence: 99%

“…Sonstr ö m et al [133] discussed that the ligands could effi ciently modify the metalsupport interaction, and the benefi cial interaction remediated CO poison of the catalyst at low temperatures and, hence, much higher activity. It is worth noting that some well-defi ned support materials have become available, such as the different shapes of TiO 2 nanocrystals [135,136] , highly ordered mesoporous supports of γ -Al 2 O 3 [137] , SiO 2 [138] , aluminosilicate such as MCM-41 [139] , MCM-48 [132] , ZSM-5 [139] , SBA-15 [140] , TS-1 [141] , mesoporous carbon [142] , and so forth. Combining these well-defi ned supports with welldefi ned metal nanoparticles is anticipated to provide new opportunities for in-depth catalytic research.…”

Section: Metal-support Interactionsmentioning

confidence: 99%

The impacts of nanotechnology on catalysis by precious metal nanoparticles

Jin

2012

Nanotechnology Reviews

139

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This review article focuses on the impacts of recent advances in solution phase precious metal nanoparticles on heterogeneous catalysis. Conventional nanometal catalysts suffer from size polydispersity. The advent of nanotechnology has signifi cantly advanced the techniques for preparing uniform nanoparticles, especially in solution phase synthesis of precious metal nanoparticles with excellent control over size, shape, composition and morphology, which have opened up new opportunities for catalysis. This review summarizes some recent catalytic research by using well-defi ned nanoparticles, including shape-controlled nanoparticles, high index-faceted polyhedral nanocrystals, nanostructures of different morphology (e.g., coreshell, hollow, etc.), bi-and multi-metallic nanoparticles, as well as atomically precise nanoclusters. Such well-defi ned nanocatalysts provide many exciting opportunities, such as identifying the types of active surface atoms (e.g., corner and edge atoms) in catalysis, the effect of surface facets on catalytic performance, and obtaining insight into the effects of size-induced electron energy quantization in ultra-small metal nanoparticles on catalysis. With well-defi ned metal nanocatalysts, many fundamentally important issues are expected to be understood much deeper in future research, such as the nature of the catalytic active sites, the metalsupport interactions, the effect of surface atom arrangement, and the atomic origins of the structure-activity and the structure-selectivity relationships.

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Vapor-Phase Epoxidation of Propene Using H2 and O2 over Au/Ti–MCM-48

Cited by 224 publications

References 34 publications

Gold on titania: Effect of preparation method in the liquid phase oxidation

Gold on titania: Effect of preparation method in the liquid phase oxidation

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

The impacts of nanotechnology on catalysis by precious metal nanoparticles

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