The catalytic activity and defect structure of zinc chromate

1991 ◽  
Vol 8 (5-6) ◽  
pp. 385-389 ◽  
Author(s):  
R. A. Jackson ◽  
C. R. A. Catlow ◽  
J. M. Thomas
Keyword(s):  
Catalytic Activity ◽  
Defect Structure ◽  
Zinc Chromate

Interplay between Defect Structure and Catalytic Activity in the Mo10−xVxOy Mixed-Oxide System

ChemPhysChem ◽  
2011 ◽  
Vol 12 (18) ◽  
pp. 3578-3583 ◽  
Author(s):  
Peter Jakes ◽  
Nina Blickhan ◽  
Tim Jekewitz ◽  
Alfons Drochner ◽  
Herbert Vogel ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxide ◽  
Defect Structure ◽  
Oxide System

ELECTRONIC STRUCTURE AND REACTIVITY OF TM-DOPED La1-xSrxCoO3 (TM = Ni, Fe) CATALYSTS

2002 ◽  
Vol 09 (01) ◽  
pp. 277-283 ◽  
Author(s):  
S. C. GRICE ◽  
W. R. FLAVELL ◽  
A. G. THOMAS ◽  
S. WARREN ◽  
P. G. MARR ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Defect Structure ◽  
Decomposition Reaction ◽  
Surface Reactivity ◽  
Local Defect ◽  
Water Binding ◽  
Crotyl Alcohol ◽  
Doped Materials ◽  
Electron Holes

The catalytic properties of LaCoO 3 in the oxidation of organic molecules in aqueous solution are explored as a function of doping with both Sr substitution for La and Fe and Ni substitution for Co. VUV photoemission is used to explore the surface reactivity of the ceramic catalysts in aqueous solution, using H 2 O as a probe molecule. These measurements are complemented by EXAFS and XANES measurements designed to probe the local defect structure and by GC measurements of catalytic activity in the aqueous epoxidation of crotyl alcohol. We relate the observed catalytic activity to the defect structure of the doped materials. In Ni-doped materials, oxygen vacancies appear to be the predominant defect, whereas in Fe-doped samples, electron holes are stabilised on Fe, leading to very different behaviour in oxidation. The surface reactivity to water is also influenced by the TM d electron count, with water binding more strongly to Fe-doped materials than to those containing Ni. The influence of these factors on the rate of the unwanted hydrogen peroxide decomposition reaction and hence on activity in epoxidation is discussed.

Electron Microscope Observations of Mechanical Metamorphism in Iron Meteorites

1970 ◽  
Vol 28 ◽  
pp. 488-489
Author(s):  
D. Faulkner ◽  
G.W. Lorimer ◽  
H.J. Axon
Keyword(s):  
Electron Microscope ◽  
Defect Structure ◽  
Shock Loading ◽  
List Type ◽  
Iron Meteorites

It is now generally accepted that meteorites are fragments produced by the collision of parent bodies of asteroidal dimensions. Optical metallographic evidence suggests that there exists a group of iron meteorites which exhibit structures similar to those observed in explosively shock loaded iron. It seems likely that shock loading of meteorites could be produced by preterrestrial impact of their parent bodies as mentioned above.We have therefore looked at the defect structure of one of these meteorites (Trenton) and compared the results with those made on a) an unshocked ‘standard’ meteorite (Canyon Diablo)b) an artificially shocked ‘standard’ meteorite (Canyon Diablo) andc) an artificially shocked specimen of pure α-iron.

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

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