Redox Properties of Metal Oxides

ChemInform ◽  
2006 ◽  
Vol 37 (10) ◽  
Author(s):  
Benjaram M. Reddy
Keyword(s):  
Metal Oxides ◽  
Redox Properties

scholarly journals Thermomechanical and Dielectric Properties Mesocomposites Based Polyepoxy, Metal Oxides and Polyaniline Hardened in Constant Physical Fields

2019 ◽  
Vol 16 (4) ◽  
pp. 726-733
Author(s):  
Y.V. Bardadym ◽  
V.O. Vilensky
Keyword(s):  
Dielectric Properties ◽  
Metal Oxides ◽  
Topological Structure ◽  
Three Dimensional ◽  
Decisive Role ◽  
Redox Properties ◽  
External Factors ◽  
Acid Base ◽  
Structure Changes ◽  
Physical Fields

The specimens of polyepoxy and mesocomposites on the base metal oxides CdO, PbO, Cr2O3, or mixtures thereof in the presence of polyaniline have been studied by methods of thermomechanical and dielectric analsis. Blending physical fields during curing samples stimulates reduction of activation energy, but also contributes to the glass transition temperature and confirms the conclusion set conformational change in the interstitial fragments forming a grid Chemical oxirane polymers under the influence of external physical fields. Differences tanhesa dielectric loss determined topological structure changes due to the influence of external factors on the reaction polipryyednannya and forming a three-dimensional grid. It was found decisive role interaction EP « МеО turnaround in determining the structure and characteristics mezokompozytiv based acid-base properties of metal oxide. Therefore, the use of metal oxides with different redox properties makes it possible to widely change thermomechanical and dielectric properties.

New crystalline complex metal oxides created by unit-synthesis and their catalysis based on porous and redox properties

2016 ◽  
Vol 188 ◽  
pp. 81-98 ◽  
Author(s):  
Zhenxin Zhang ◽  
Satoshi Ishikawa ◽  
Yuta Tsuboi ◽  
Masahiro Sadakane ◽  
Toru Murayama ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Metal Ion ◽  
Structural Complexity ◽  
Acid Catalyst ◽  
Molecular Wires ◽  
Redox Properties ◽  
Crystalline Complex ◽  
Practical Applications ◽  
Complex Metal ◽  
Complex Metal Oxides

The development of new complex metal oxides having structural complexity suitable for solid-state catalysis is of great importance in fundamental catalysis research and practical applications. However, examples of these materials are rare. Herein, we report two types of crystalline complex metal oxides with new structures and their catalytic properties. The first one is an all-inorganic ε-Keggin polyoxometalate-based material with intrinsic microporosity. The framework of the material is formed by the assembly of ε-Keggin polyoxomolybdate units with metal ion linkers in a diamondoid topology. The micropores of the material can be opened without change of the structures, and the material adsorbs small molecules. This material has both redox properties and acidity and can be applied to O2 adsorption, selective oxidation of methacrolein, and hydrolysis of cellobiose. The other material is a crystalline metal oxide based on molecular nanowires. The hexagonal POM units stack along the c axis to form prismatic clusters as molecular wires. The molecular wires further assemble in a hexagonal fashion to form the crystals, and NH4+ and water are present in between the molecular wires. The material is active as an acid catalyst for cellobiose conversion.

scholarly journals Selective Oxidation of Isobutane to Methacrylic Acid and Methacrolein: A Critical Review

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 769
Author(s):  
Li Zhang ◽  
Sébastien Paul ◽  
Franck Dumeignil ◽  
Benjamin Katryniok
Keyword(s):  
Metal Oxides ◽  
Selective Oxidation ◽  
Methacrylic Acid ◽  
Critical Review ◽  
Low Cost ◽  
Academic Research ◽  
Redox Properties ◽  
Main Reaction ◽  
Reaction Conditions ◽  
Process Complexity

Selective oxidation of isobutane to methacrolein (MAC) and methacrylic acid (MAA) has received great interest both in the chemical industry and in academic research. The advantages of this reaction originate not only from the low cost of the starting material and reduced process complexity, but also from limiting the use of toxic reactants and the production of wastes. Successive studies and reports have shown that heteropolycompounds (HPCs) with Keggin structure (under the form of partially neutralized acids with increased stability) can selectively convert isobutane to MAA and MAC due to their strong and tunable acidity and redox properties. This review hence aims to discuss the Keggin-type HPCs that have been used in recent years to catalyze the oxidation of isobutane to MAA and MAC, and to review alternative metal oxides with proper redox properties for the same reaction. In addition, the influence of the main reaction conditions will be discussed.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

Problems with oxygen analysis in the system MgO-Al2O3-SiO2 with the electron microprobe

1992 ◽  
Vol 50 (2) ◽  
pp. 1624-1625
Author(s):  
Michel Fialin ◽  
Guy Rémond
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Electrostatic Charge ◽  
Carbon Layer ◽  
Sample Holder ◽  
Rock Matrix ◽  
Electrical Discharges ◽  
Thin Carbon ◽  
Beam Instabilities

Oxygen-bearing minerals are generally strong insulators (e.g. silicates), or if not (e.g. transition metal oxides), they are included within a rock matrix which electrically isolates them from the sample holder contacts. In this respect, a thin carbon layer (150 Å in our laboratory) is evaporated on the sections in order to restore the conductivity. For silicates, overestimated oxygen concentrations are usually noted when transition metal oxides are used as standards. These trends corroborate the results of Bastin and Heijligers on MgO, Al2O3 and SiO2. According to our experiments, these errors are independent of the accelerating voltage used (fig.l).Owing to the low density of preexisting defects within the Al2O3 single-crystal, no significant charge buildup occurs under irradiation at low accelerating voltage (< 10keV). As a consequence, neither beam instabilities, due to electrical discharges within the excited volume, nor losses of energy for beam electrons before striking the sample, due to the presence of the electrostatic charge-induced potential, are noted : measurements from both coated and uncoated samples give comparable results which demonstrates that the carbon coating is not the cause of the observed errors.

METAL-OXIDES COMPOSITES FOR BaFe12O19 PERMANENT MAGNETS

1977 ◽  
Vol 38 (C1) ◽  
pp. C1-333-C1-336 ◽  
Author(s):  
P. CAVALLOTTI ◽  
R. ROBERTI ◽  
G. CAIRONI ◽  
G. ASTI
Keyword(s):  
Metal Oxides ◽  
Permanent Magnets

Influence of the Polarization of Molecules of Metal Oxides on the Diffusion Coefficient in Smoky Plasmas

2014 ◽  
Vol 59 (4) ◽  
pp. 401-404
Author(s):  
G.S. Dragan ◽  
◽  
K.V. Kolesnikov ◽  
V.M. Ulianytskyi ◽  
◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Metal Oxides
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