Photocatalyzed preferential oxidation of CO under simulated sunlight using Au–transition metal oxide–sepiolite catalysts

2020 ◽  
Vol 49 (13) ◽  
pp. 3946-3955 ◽  
Author(s):  
Elena Rodríguez Aguado ◽  
Juan Antonio Cecilia ◽  
Antonia Infantes-Molina ◽  
Aldo Talon ◽  
Loretta Storaro ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Atmospheric Pressure ◽  
Simulated Sunlight ◽  
Preferential Oxidation ◽  
Oxidation Of Co ◽  
Preferential Oxidation Of Co ◽  
Simulated Solar Light ◽  
Solar Light Irradiation

A series of Au–transition metal oxides supported on sepiolite was tested in the preferential oxidation of CO in an excess of H2 under simulated solar light irradiation and in the absence of light, at 30 °C and atmospheric pressure.

Oxidation of CO on nanocrystalline ceria promoted by transition metal oxides

2009 ◽  
Vol 427 (2) ◽  
pp. 186-189 ◽  
Author(s):  
M. S. Yakimova ◽  
V. K. Ivanov ◽  
O. S. Polezhaeva ◽  
A. A. Trushin ◽  
A. S. Lermontov ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Oxidation Of Co ◽  
Nanocrystalline Ceria

scholarly journals Total Oxidation of Isopropanol in the Liquid Phase, under Atmospheric Pressure and Low Temperature, on Transition Metal Oxides Catalysts Cr2O3 and Fe2O3

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Younes Dehmani ◽  
Sadik Abouarnadasse
Keyword(s):  
Liquid Phase ◽  
Low Temperature ◽  
Transition Metal ◽  
Metal Oxides ◽  
Chromium Oxide ◽  
Transition Metal Oxides ◽  
Atmospheric Pressure ◽  
Specific Activity ◽  
Oxidation Products ◽  
Precipitation Method

Isopropanol oxidation in the liquid phase under atmospheric pressure and low temperature has been studied in the presence of transition metal oxides (Cr2O3 and Fe2O3) prepared by the precipitation method. These solids characterized by structural analyses (FTIR and XRD) and textural analysis (BET) have led to results in line with those reported in the literature. Chromium oxide has a much more developed texture, with a specific surface area and pore volume 5 times larger than iron oxide. Both of the solids show a good specific activity and led to acetone and carbon dioxide to be formed as the only oxidation products of isopropanol. However, chromium oxide is more active. The initial catalytic activity for the latter is varying between 4.87 ∗ 10−6 and 5.79 ∗ 10−6 mol·g−1·s−1 with temperature range from 40 to 80°C. Kinetic study shows that the reaction follows a successive scheme: isopropanol ⟶ acetone ⟶ CO2 involving a redox mechanism. The low value of the activation apparent energy (Ea.(Cr2O3) = 2.87 kJ·mol−1 < Ea. (Fe2O3) = 5.37 kJ·mol−1) justifies the relatively higher activity observed for chromium oxide.

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.

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