The Effect of Hydrogen on the Carbonaceous Layer Formed on Molybdenum Model Catalysts during High Temperature Propylene Metathesis

1998 ◽  
Vol 173 (1) ◽  
pp. 172-176 ◽  
Author(s):  
G. Wu ◽  
B. Bartlett ◽  
W.T. Tysoe
Keyword(s):  
High Temperature ◽  
Model Catalysts ◽  
Propylene Metathesis

scholarly journals Pt/ceria thin film model catalysts after high-temperature reduction: a (HR)TEM study

Vacuum ◽  
2003 ◽  
Vol 71 (1-2) ◽  
pp. 71-76 ◽  
Author(s):  
S. Penner ◽  
G. Rupprechter ◽  
H. Sauer ◽  
D.S. Su ◽  
R. Tessadri ◽  
...  
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Model Catalysts ◽  
Film Model ◽  
Temperature Reduction ◽  
Thin Film Model

scholarly journals High-temperature Fischer-Tropsch synthesis over FeTi mixed oxide model catalysts: Tailoring activity and stability by varying the Ti/Fe ratio

2017 ◽  
Vol 533 ◽  
pp. 38-48 ◽  
Author(s):  
Vera P. Santos ◽  
Liam Borges ◽  
Sina Sartipi ◽  
Bart van der Linden ◽  
A. Iulian Dugulan ◽  
...  
Keyword(s):  
High Temperature ◽  
Mixed Oxide ◽  
Tropsch Synthesis ◽  
Model Catalysts ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis

XRPD/TEM studies of model high-temperature shift catalysts

2006 ◽  
Vol 39 (4) ◽  
pp. 519-526 ◽  
Author(s):  
Rune E. Johnsen ◽  
Alfons M. Molenbroek ◽  
Kenny Ståhl
Keyword(s):  
High Temperature ◽  
Iron Oxide ◽  
Crystallite Size ◽  
Rietveld Method ◽  
Temperature Shift ◽  
Average Crystallite Size ◽  
Model Catalysts ◽  
Crystallite Sizes ◽  
Scherrer Equation

The combination of transmission electron microscopy (TEM) andin situX-ray powder diffraction (XRPD) for the investigation of four model high-temperature shift catalysts makes it possible to obtain and compare information concerning the crystallite and particle shapes and sizes before, during and after the reduction of the synthesized hematite-based model catalyst to the active magnetite-based catalyst. Two chromium-containing iron oxide model catalysts and two pure iron oxide model catalysts were synthesized from hydrated chloride or nitrate salts, resulting in particles with different shapes and sizes. The average crystallite sizes of four model catalysts were determined by XRPD using the Scherrer equation before and after the reduction. The crystallite sizes determined before the reduction were compared with particles sizes determined from TEM images of the same samples. These sizes were generally in good agreement. By using the Rietveld method combined with the Scherrer equation and the Lorentzian Scherrer broadening parameters, the development of the average crystallite size during thein situreduction was demonstrated. This showed that the average crystallite size of the remaining hematite increases when the reduction begins. Additionally, the average crystallite sizes of the reduced samples showed that the chromium-containing model catalysts have the smallest increase in the overall crystallite size.

High Temperature Stability of Ceria-Zirconia Supported Pd Model Catalysts

1998 ◽  
Author(s):  
Jean-Pierre Cuif ◽  
Steve Deutsch ◽  
Mike Marczi ◽  
Hung-Wen Jen ◽  
George W. Graham ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Stability ◽  
Model Catalysts ◽  
High Temperature Stability ◽  
Supported Pd

Mesoporous Multicomponent Nanocomposite Colloidal Spheres: Ideal High-Temperature Stable Model Catalysts

2011 ◽  
Vol 50 (16) ◽  
pp. 3725-3729 ◽  
Author(s):  
Chen Chen ◽  
Caiyun Nan ◽  
Dingsheng Wang ◽  
Qiao Su ◽  
Haohong Duan ◽  
...  
Keyword(s):  
High Temperature ◽  
Model Catalysts ◽  
Stable Model ◽  
Colloidal Spheres

Mesoporous Multicomponent Nanocomposite Colloidal Spheres: Ideal High-Temperature Stable Model Catalysts

2011 ◽  
Vol 123 (16) ◽  
pp. 3809-3813 ◽  
Author(s):  
Chen Chen ◽  
Caiyun Nan ◽  
Dingsheng Wang ◽  
Qiao Su ◽  
Haohong Duan ◽  
...  
Keyword(s):  
High Temperature ◽  
Model Catalysts ◽  
Stable Model ◽  
Colloidal Spheres

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

Lattice Imaging of Grain Boundaries in Ceramics

1977 ◽  
Vol 35 ◽  
pp. 114-115
Author(s):  
D. R. Clarke ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundaries ◽  
High Temperature Strength ◽  
Current Interest ◽  
Lattice Imaging ◽  
Special Significance ◽  
Structural Applications ◽  
Refractory Ceramics

Grain boundaries have long held a special significance to ceramicists. In part, this has been because it has been impossible until now to actually observe the boundaries themselves. Just as important, however, is the fact that the grain boundaries and their environs have a determing influence on both the mechanisms by which powder compaction occurs during fabrication, and on the overall mechanical properties of the material. One area where the grain boundary plays a particularly important role is in the high temperature strength of hot-pressed ceramics. This is a subject of current interest as extensive efforts are being made to develop ceramics, such as silicon nitride alloys, for high temperature structural applications. In this presentation we describe how the techniques of lattice fringe imaging have made it possible to study the grain boundaries in a number of refractory ceramics, and illustrate some of the findings.

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