Mesostructure controllable ZSM-5 single crystals supported Pd/transition metal oxides: efficient and reusable catalysts for selective oxidation under aerobic conditions

2016 ◽  
Vol 24 (2) ◽  
pp. 297-303 ◽  
Author(s):  
Chen Liu ◽  
Qin Wu ◽  
Jinjun Peng ◽  
Chenze Qi ◽  
Fujian Liu
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Single Crystals ◽  
Selective Oxidation ◽  
Transition Metal Oxides ◽  
Aerobic Conditions ◽  
Supported Pd

scholarly journals Selective Oxidation of Glycerol Using 3% H2O2 Catalyzed by Supported Nano-Au Catalysts

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 505 ◽  
Author(s):  
Xiaoli Wang ◽  
Gongde Wu ◽  
Tongfa Jin ◽  
Jie Xu ◽  
Shihao Song
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Selective Oxidation ◽  
Mixed Oxide ◽  
Transition Metal Oxides ◽  
Mixed Oxides ◽  
Catalytic Performance ◽  
Glyceric Acid ◽  
Glycerol Conversion ◽  
Composition And Structure

A series of transition metal oxides or mixed oxides supported nano-Au catalysts were prepared for the selective oxidation of glycerol to glyceric acid using 3% H2O2. It was found that the composition and structure of supports significantly influenced the catalytic performance of catalysts. The mesoporous trimetal mixed oxide (CuNiAlO) supported nano-Au catalysts were more active in comparison with the others. In the present catalytic system, the highest glycerol conversion was 90.5%, while the selectivity of glyceric acid could reach 72%. Moreover, the catalytic performance remained after 11 times of reaction.

Single-Crystal Synthesis

2021 ◽  
pp. 161-178
Author(s):  
Gang Cao ◽  
Lance E. DeLong
Keyword(s):  
Crystal Growth ◽  
Transition Metal ◽  
Metal Oxides ◽  
Single Crystals ◽  
Crystal Structures ◽  
Transition Metal Oxides ◽  
Magnetic Moments ◽  
Spin Orbit ◽  
Spin Orbit Interactions ◽  
Almost All

Growing single crystals of 4d- and 5d-transition metal oxides is often difficult, as they tend to form incongruently, as well as having high vapor pressure and high melting points. Two crystal growth techniques are commonly used for transition metal oxides—flux and floating-zone techniques; each has advantages and disadvantages. An established capability in both techniques makes it possible to grow single crystals of almost all stable materials. Some basic aspects of both techniques are discussed, and a few general remarks on crystal growth of 4d- and 5d-transition metal oxides are presented. Crystal structures of most 4d- and 5d-transition metal oxides are inherently distorted. An innovative “field-altering” technique is under development, in which an applied magnetic field aligns magnetic moments and, through strong spin-orbit interactions and magnetoelastic coupling, alters crystal structures at high temperatures. Preliminary results show that a field-altering technology is highly effective for resolving physical properties of spin-orbit-coupled oxides.

Redox-Active Zeolitic Transition Metal Oxides Based on ε-Keggin Units for Selective Oxidation

2019 ◽  
Vol 58 (9) ◽  
pp. 6283-6293 ◽  
Author(s):  
Zhenxin Zhang ◽  
Satoshi Ishikawa ◽  
Qianqian Zhu ◽  
Toru Murayama ◽  
Masahiro Sadakane ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Selective Oxidation ◽  
Transition Metal Oxides ◽  
Redox Active

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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