Control of Reaction Selectivity via Surface Oxygen Coverage:  Thermal Decomposition of Azomethane on Rh(111)

1997 ◽  
Vol 101 (33) ◽  
pp. 6436-6442 ◽  
Author(s):  
C. W. J. Bol ◽  
J. D. Kovacs ◽  
M. Chen ◽  
C. M. Friend
Keyword(s):  
Thermal Decomposition ◽  
Surface Oxygen ◽  
Reaction Selectivity ◽  
Oxygen Coverage

The effect of the gradual thermal decomposition of surface oxygen species on the chemical and catalytic properties of oxidized activated carbon

Carbon ◽  
2002 ◽  
Vol 40 (14) ◽  
pp. 2627-2639 ◽  
Author(s):  
Grzegorz S Szymański ◽  
Zbigniew Karpiński ◽  
Stanisław Biniak ◽  
Andrzej Świa̧tkowski
Keyword(s):  
Thermal Decomposition ◽  
Activated Carbon ◽  
Catalytic Properties ◽  
Oxygen Species ◽  
Surface Oxygen ◽  
Oxidized Activated Carbon

EFFECT OF ELEY–RIDEAL PROCESS ON THE PHASE DIAGRAM OF A MONOMER–DIMER CATALYTIC REACTION ON (001) SURFACE AND SUBSURFACE OF A SIMPLE CUBIC STRUCTURE

2004 ◽  
Vol 15 (09) ◽  
pp. 1215-1225 ◽  
Author(s):  
A. U. QAISRANI ◽  
K. M. KHAN ◽  
M. KHALID
Keyword(s):  
Phase Diagram ◽  
Catalytic Reaction ◽  
Experimental Situation ◽  
Surface Site ◽  
Surface Oxygen ◽  
Simple Cubic ◽  
Oxygen Coverage ◽  
Cubic Structure

We have investigated the effects of the Eley–Rideal (ER) process on the phase diagram of the Langmuir–Hinshelwood (LH) type monomer–dimer ( CO – O 2) catalytic reaction on (001) surface and subsurface of a simple cubic structure. With the consideration of a new pathway in which a dimer is adsorbed in such a way that it takes one surface site whereas second site may be from a surface or from a subsurface, a situation close to experiments is observed, i.e., with slight introduction of the monomer ( CO ), the production of AB2 starts. In this case, the qualitative trend of surface oxygen coverage is consistent with the experimental situation.

First-Principles Study of H2O Adsorption on Oxygen-Covered Fe Surface

2012 ◽  
Vol 706-709 ◽  
pp. 1481-1484 ◽  
Author(s):  
Norio Nunomura ◽  
Satoshi Sunada
Keyword(s):  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Water Molecules ◽  
First Principle ◽  
Surface Oxygen ◽  
Functional Theory ◽  
First Principle Calculations ◽  
Oxygen Coverage ◽  
Adsorption Of Water

We present the results from first principle calculations of H2O adsorption on oxygen-covered Fe (100) surface. The calculations are based on a density-functional theory, surface modeling which uses supercell slab models. As a surface oxygen coverage increases, the surface is not activated, which makes the adsorption of water molecules on Fe surface unfavorable. It has been found that the surface covered oxygen exerts an influence on the adsorption of H2O molecule on Fe surface.

Atomic level structure of TiO2(110) as a function of surface oxygen coverage

1994 ◽  
Vol 302 (1-2) ◽  
pp. L263-L268 ◽  
Author(s):  
Michael Sander ◽  
Thomas Engel
Keyword(s):  
Level Structure ◽  
Atomic Level ◽  
Surface Oxygen ◽  
Oxygen Coverage

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

Observations of the Thermal Decomposition of Brucite

1968 ◽  
Vol 26 ◽  
pp. 446-447
Author(s):  
P. L. Burnett ◽  
W. R. Mitchell ◽  
C. L. Houck
Keyword(s):  
Thermal Decomposition ◽  
Magnesium Oxide ◽  
Basal Plane ◽  
Magnesium Ions ◽  
A Value ◽  
Reaction Proceeds

Natural Brucite (Mg(OH)2) decomposes on heating to form magnesium oxide (MgO) having its cubic ﹛110﹜ and ﹛111﹜ planes respectively parallel to the prism and basal planes of the hexagonal brucite lattice. Although the crystal-lographic relation between the parent brucite crystal and the resulting mag-nesium oxide crystallites is well known, the exact mechanism by which the reaction proceeds is still a matter of controversy. Goodman described the decomposition as an initial shrinkage in the brucite basal plane allowing magnesium ions to shift their original sites to the required magnesium oxide positions followed by a collapse of the planes along the original <0001> direction of the brucite crystal. He noted that the (110) diffraction spots of brucite immediately shifted to the positions required for the (220) reflections of magnesium oxide. Gordon observed separate diffraction spots for the (110) brucite and (220) magnesium oxide planes. The positions of the (110) and (100) brucite never changed but only diminished in intensity while the (220) planes of magnesium shifted from a value larger than the listed ASTM d spacing to the predicted value as the decomposition progressed.

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