Kinetic model for sintering of supported metal particles with improved size-dependent energetics and applications to Au onTiO2(110)

2007 ◽  
Vol 75 (3) ◽  
Author(s):  
Stephen C. Parker ◽  
Charles T. Campbell
Keyword(s):  
Kinetic Model ◽  
Metal Particles ◽  
Size Dependent ◽  
Supported Metal

HREM image simulations for supported metal particle catalysts

1993 ◽  
Vol 51 ◽  
pp. 736-737 ◽  
Author(s):  
Ming-Hui Yao ◽  
David J. Smith
Keyword(s):  
Fine Particles ◽  
Amorphous Material ◽  
Chemical Properties ◽  
Morphological Features ◽  
Metal Particles ◽  
Plan View ◽  
Profile View ◽  
Imaging Conditions ◽  
Image Simulations ◽  
Supported Metal

The chemical properties of catalysts often depend on the size, shape and structure of the supported metal particles. To characterize these morphological features and relate them to catalysis is one of the main objectives for HREM study of catalysts. However, in plan view imaging, details of the shape and structure of ultra-fine supported particles (<2nm) are often obscured by the overlapping contrast from the support, and supported sub-nanometer particles are sometimes even invisible. Image simulations may help in the interpretation at HREM images of supported particles in particular to extract useful information about the size, shape and structure of the particles. It should also be a useful tool for evaluating the imaging conditions in terms of visibility of supported particles. P. L. Gai et al have studied contrast from metal particles supported on amorphous material using multislice simulations. In order to better understand the influence of a crystalline support on the visibility and apparent morphological features of supported fine particles, we have calculated images of Pt and Re particles supported on TiO2(rutile) in both plan view and profile view.

Surface Study of Supported Metal Particles by129XeNMR

1995 ◽  
Vol 74 (16) ◽  
pp. 3277-3280 ◽  
Author(s):  
A. Bifone ◽  
T. Pietrass ◽  
J. Kritzenberger ◽  
A. Pines ◽  
B. F. Chmelka
Keyword(s):  
Metal Particles ◽  
Surface Study ◽  
Supported Metal

Size-dependent catalytic activity of supported metal clusters

Nature ◽  
1994 ◽  
Vol 372 (6504) ◽  
pp. 346-348 ◽  
Author(s):  
Z. Xu ◽  
F.-S. Xiao ◽  
S. K. Purnell ◽  
O. Alexeev ◽  
S. Kawi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metal Clusters ◽  
Size Dependent ◽  
Supported Metal Clusters ◽  
Supported Metal

scholarly journals In-situ Study of Coarsening Mechanisms of Supported Metal Particles in Reducing Gas

2015 ◽  
Vol 21 (S3) ◽  
pp. 643-644
Author(s):  
S.Y. Zhang ◽  
Matteo Cargnello ◽  
Christopher B. Murray ◽  
George W. Graham ◽  
Xiaoqing Pan
Keyword(s):  
Metal Particles ◽  
In Situ Study ◽  
Reducing Gas ◽  
Supported Metal

Carbon Fibrils Mechanism of Growth and Utilization as a Catalyst Support

1994 ◽  
Vol 368 ◽  
Author(s):  
John W. Geus ◽  
A. J. Van Dillen ◽  
Marco S. Hoogenraad
Keyword(s):  
Mechanical Strength ◽  
Active Carbon ◽  
Circular Cross Section ◽  
Metal Particles ◽  
High Dispersion ◽  
Average Pore ◽  
High Mechanical Strength ◽  
Very High ◽  
Mechanism Of Growth ◽  
Supported Metal

ABSTRACTEspecially with the production of fine chemicals catalytic reactions are being performed in which solid catalysts suspended in liquids are used. Carbon is stable in both acid and alkaline liquids and is not preferentially wetted by water. Carbon is therefore an attractive support for catalysts to be used in liquid-phase reactions. The relatively low diffusion coefficients in liquids call for catalyst bodies having wide pores and dimensions between 1 and 10 μm. Since particles smaller than 1 μm cannot be readily separated from liquids, attrition of carbon support bodies must be avoided. However, it is difficult to produce active carbon bodies of 1 to 10 μm of a high mechanical strength. Also with gas-phase reactions, the low mechanical strength of active carbon bodies limits the applicability of active carbon.From supported metal particles carbon filaments of a diameter between 10 and 300 nm can be grown rapidly. The diameter is generally of the same order of magnitude as the size of the metal particles. The graphite layers within the fibrils, that have a circular cross-section, are oriented either parallel to the fibril axis or at an angle, which leads to cone-shaped graphite layers. The mechanism of growth of carbon fibrils from supported metal particles will be dealt with. The parallel orientation of the graphite layers leads to a very high mechanical strength, while the porous structure is extremely open. A representative value for the surface area is 225 m2/g and for the pore volume 1.6 ml/g, which leads to an average pore dimension of 28 nm.To apply active precursors, such as, palladium salts, the surface of the carbon fibrils must be oxidized, e.g., by treatment with nitric acid. A very high dispersion of palladium can thus be achieved. The dispersion of components active in hydrogenation can be assessed by the ability to react the support with hydrogen to methane. The activity of catalyst on carbon fibrils in the hydrogenation of nitrobenzene as well as the filterability of carbon fibril catalysts will be compared with that of commercial catalysts.

Size-Dependent Molecular Dissociation on Mass-Selected, Supported Metal Clusters

1998 ◽  
Vol 120 (37) ◽  
pp. 9668-9671 ◽  
Author(s):  
U. Heiz ◽  
F. Vanolli ◽  
A. Sanchez ◽  
W.-D. Schneider
Keyword(s):  
Metal Clusters ◽  
Molecular Dissociation ◽  
Size Dependent ◽  
Supported Metal Clusters ◽  
Supported Metal
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