scholarly journals Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles

2014 ◽  
Vol 12 (19) ◽  
pp. 3026-3036 ◽  
Author(s):  
Oleg V. Larionov ◽  
David Stephens ◽  
Adelphe M. Mfuh ◽  
Hadi D. Arman ◽  
Anastasia S. Naumova ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Active Species ◽  
Catalytically Active ◽  
Synthetic Studies ◽  
Catalyzed Oxidation ◽  
Shed Light

Mechanistic and synthetic studies of the Mo/P-catalyzed N-oxidation of N-heterocycles with hydrogen peroxide shed light on the role and nature of the catalytically active species.

An ESR study of irradiated mixtures of hydrogen peroxide and Cu(II) complexes at 77 K

1988 ◽  
Vol 53 (12) ◽  
pp. 3080-3088 ◽  
Author(s):  
Pavel Stopka
Keyword(s):  
Hydrogen Peroxide ◽  
High Pressure ◽  
Catalytic Activity ◽  
Oxalic Acid ◽  
Hydroxyl Radicals ◽  
Room Temperature ◽  
Active Species ◽  
Mercury Lamp ◽  
Catalytically Active ◽  
High Concentrations

When aqueous solutions containing hydrogen peroxide and CuSO4 are irradiated by a high-pressure mercury lamp at room temperature and at 77 K, hydrogen peroxide decomposes and hydroxyl radicals generated in high concentrations coordinate to CuSO4. The catalytic activity of Cu(II), which depends on the choice of the ligand (triene, diene, ethylenediamine, ammonia, EDTA, oxalic acid and glycerine) and the proportion between the monomeric and dimeric forms of the Cu(II) complex, shows a maximum at a concentration of 10-4 mol dm-3. The catalytically active species is the monomeric Cu(II) complex, the dimer being inactive.

Sewage sludge as a precursor of adsorbents/catalysts for environmental applications

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Ros ◽  
C. Canals-Batlle ◽  
M.A. Lillo-Ródenas ◽  
E. Fuente ◽  
M. A. Montes-Morán ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Room Temperature ◽  
Waste Water Treatment ◽  
Textural Properties ◽  
Active Species ◽  
Elemental Sulphur ◽  
Gaseous Emissions ◽  
Removal Experiments ◽  
Catalytically Active

This paper focuses on the valorisation of solid residues obtained from the thermal treatment of sewage sludge. In particular, sewage sludge samples were collected from two waste water treatment plants (WWTPs) with different sludge line basic operations. After drying, sludges were heated up to 700 °C in appropriate ovens under diluted air (gasification) and inert (pyrolysis) atmospheres. The solids obtained, as well as the dried (raw) sludges, were characterised to determine their textural properties and chemical composition, including the speciation of their inorganic fraction. All the materials under study were employed as adsorbents/catalysts in H2S removal experiments at room temperature. It was found that, depending on the particular sludge characteristics, outstanding results can be achieved both in terms of retention capacities and selectivity. Some of the solids outperform commercially available sorbents specially designed for gaseous emissions control. In these adsorbents/catalysts, H2S is selectively oxidised to elemental sulphur most likely due to the presence of inorganic, catalytically active species. The role of the carbon-enriched part on these solids is also remarked.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

Probing the Catalytically Active Species in POM‐catalysed DNA‐model Hydrolysis

2021 ◽  
Author(s):  
Frederico F Martins ◽  
Ángel Sánchez-González ◽  
Jose Lanuza ◽  
Haralampos N. Miras ◽  
Xabier Lopez ◽  
...  
Keyword(s):  
Active Species ◽  
Catalytically Active

scholarly journals Shedding light on the nature of the catalytically active species in photocatalytic reactions using Bi2O3 semiconductor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Paola Riente ◽  
Mauro Fianchini ◽  
Patricia Llanes ◽  
Miquel A. Pericàs ◽  
Timothy Noël
Keyword(s):  
Experimental Studies ◽  
Heterogeneous Photocatalysis ◽  
Active Species ◽  
Organic Transformations ◽  
Alkyl Bromides ◽  
Catalytically Active ◽  
Visible Light Driven ◽  
Photocatalytic Reactions ◽  
Insight Into ◽  
Photocatalytic Processes

AbstractThe importance of discovering the true catalytically active species involved in photocatalytic systems allows for a better and more general understanding of photocatalytic processes, which eventually may help to improve their efficiency. Bi2O3 has been used as a heterogeneous photocatalyst and is able to catalyze several synthetically important visible-light-driven organic transformations. However, insight into the operative catalyst involved in the photocatalytic process is hitherto missing. Herein, we show through a combination of theoretical and experimental studies that the perceived heterogeneous photocatalysis with Bi2O3 in the presence of alkyl bromides involves a homogeneous BinBrm species, which is the true photocatalyst operative in the reaction. Hence, Bi2O3 can be regarded as a precatalyst which is slowly converted in an active homogeneous photocatalyst. This work can also be of importance to mechanistic studies involving other semiconductor-based photocatalytic processes.

scholarly journals Metal-catalyzed oxidation renders silver intensification selective. Applications for the histochemistry of diaminobenzidine and neurofibrillary changes.

1986 ◽  
Vol 34 (12) ◽  
pp. 1667-1672 ◽  
Author(s):  
F Gallyas ◽  
J R Wolff
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Polymerization ◽  
Silver Coating ◽  
Neurofibrillary Changes ◽  
Iodide Ions ◽  
Tissue Sections ◽  
Metal Catalyzed Oxidation ◽  
Pre Treatment ◽  
Metal Catalyzed ◽  
Catalyzed Oxidation

Physical developers can increase the visibility of end products of certain histochemical reactions, such as oxidative polymerization of diaminobenzidine and selective binding of complex silver iodide ions to Alzheimer's neurofibrillary changes. Unfortunately, this intensification by silver coating is generally superimposed on a nonspecific staining originating from the argyrophil III reaction, which also takes place when tissue sections are treated with physical developers. The present study reveals that the argyrophil III reaction can be suppressed when tissue sections are treated with certain metal ions and hydrogen peroxide before they are transferred to the physical developer. The selective intensification of Alzheimer's neurofibrillary changes requires a pre-treatment with lanthanum nitrate (10 mM/liter) and 3% hydrogen peroxide for 1 hr. The diaminobenzidine reaction can be selectively intensified when physical development is preceded by consecutive treatments with copper sulfate (10 mM/liter, pH 5, 10 min) and hydrogen peroxide (3%, pH 7, 10 min). In peroxidase histochemistry, this high-grade intensification may help to increase specificity and reduce the threshold of detectability in tracing neurons with horseradish peroxidase or in immunohistochemistry when the peroxidase-antiperoxidase method is used.

ChemInform Abstract: Sulfonic Acid Resin-Catalyzed Oxidation of Aldehydes to Carboxylic Acids by Hydrogen Peroxide.

ChemInform ◽  
2013 ◽  
Vol 44 (29) ◽  
pp. no-no
Author(s):  
Xiaomei Yang ◽  
Si Tang ◽  
Tianliang Lu ◽  
Chen Chen ◽  
Lipeng Zhou ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Carboxylic Acids ◽  
Sulfonic Acid ◽  
Acid Resin ◽  
Catalyzed Oxidation ◽  
Sulfonic Acid Resin
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