Hydrogen peroxide decomposition on a non-irradiated and gamma pre-irradiated NiO-U3O8 catalyst

1981 ◽  
Vol 46 (8) ◽  
pp. 1886-1897 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Hydrogen Peroxide ◽  
Gamma Rays ◽  
Catalytic Properties ◽  
Chemical Properties ◽  
Oxidation States ◽  
Hydrogen Peroxide Decomposition ◽  
Physico Chemical ◽  
Peroxide Decomposition ◽  
Charge Interaction ◽  
Observed Behaviour

This paper deals with some physico-chemical properties of a two component catalyst NiO-U3O8, prepared with varying ratio of both components. Special interest was given to the catalytic properties - tested by decomposition of aqueous solution of hydrogen peroxide. The study presented evidence of mutual charge interaction between both components of the catalyst. This enables one to explain the observed behaviour of the studied system on the basis of the principle of bivalent sites. A pre-irradiation of a catalyst by gamma rays leads to significant increase of the oxidation states of both catalyst components.

Reduction of two-component CuO–Cr2O3 mixed oxides and their catalytic activity

1992 ◽  
Vol 70 (7) ◽  
pp. 1914-1916 ◽  
Author(s):  
V. Múčka
Keyword(s):  
Activation Energy ◽  
Hydrogen Peroxide ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Mutual Influence ◽  
Test Reaction ◽  
Hydrogen Peroxide Decomposition ◽  
Physico Chemical ◽  
Peroxide Decomposition ◽  
Two Component

The reduction with hydrogen of the two-component mixed oxides CuO–Cr2O3 containing various amounts of both components in the whole range from 0 to 100% was studied, as well as some physico-chemical and catalytic properties. The hydrogen peroxide decomposition served as a test catalytic reaction. A significant effect of the reduction on the rate constant of the test reaction was found, as well as on the value of its apparent activation energy. Pronounced changes were observed, especially in the border ranges of the composition. This fact may be connected with the mutual influence of both components in the catalyst.

Decomposition of hydrogen peroxide on nickel oxide-manganese sesquioxide two-component catalysts and effect of ionizing radiation on them

1981 ◽  
Vol 46 (8) ◽  
pp. 1860-1875 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Nickel Oxide ◽  
Surface Area ◽  
Chemical Properties ◽  
Unit Surface Area ◽  
Hydrogen Peroxide Decomposition ◽  
Specific Catalytic Activity ◽  
Peroxide Decomposition ◽  
Two Component

The catalytic and some physico-chemical properties were studied of nickel oxide-manganese sesquioxide two-component catalysts with various proportions of the constituents. Decomposition of hydrogen peroxide in aqueous solution with the initial concentration 1.2 mol l-1 served as testing reaction. The catalyst components affect each other; the effect, being highest in the region of 20-30 mol.% manganese sesquioxide, brings about an enhanced dispersity of the system, with the result of increased surface area, increased amount of overstoichiometric oxygen and deficit in chemical analysis. Furthermore, the mutual component influencing appears in the specific catalytic activity of the system and in the amount of overstoichiometric oxygen per unit surface area, which is highest at 85 mol.% Mn2O3. A model of the mechanism is suggested for the reaction under study, based on the concept of bivalent catalytic centres, assuming that during the reaction, the high valency manganese species are gradually reduced as far as divalent manganese; this accounts for the occurrence of the observed two or three stages of hydrogen peroxide decomposition. Neither the mechanism of interaction of the two oxides nor the mechanism of the hydrogen peroxide decomposition changes on prior gamma irradiation of the catalyst. However, the irradiation affects markedly the catalytic activity of the system, the effect for catalyst of different composition being qualitatively different. Within the suggested concept of the reaction mechanism, the observed changes can be interpreted in terms of formation of non-eqilibrium charge carriers (electrons) resulting from the ionization both in the surface layer and in the catalyst bulk; after stabilization on the surface, the carriers may serve as adsorption centres for chemisorption of oxygen or may recombine with the catalytic centres of the reaction under study.

O-O bond activation with cobalt(II)-ethylenediamine complexes in ion-exchange resins

1980 ◽  
Vol 45 (6) ◽  
pp. 1780-1784 ◽  
Author(s):  
Atanas Andreev ◽  
Lachezar Prahov ◽  
Dimitar Shopov
Keyword(s):  
Ion Exchange ◽  
Bond Activation ◽  
Catalytic Properties ◽  
Decomposition Reaction ◽  
Ion Exchange Resins ◽  
Hydrogen Peroxide Decomposition ◽  
Surface Complexes ◽  
Peroxide Decomposition ◽  
Epr Parameters ◽  
Exchange Resins

The formation of Oxygen paramagnetic adducts of Co(II) containing ion-exchange resins in the presence of adsorbed ethylenediamine has been found. The EPR parameters of a complex of the type Co(III) (en)2O-2 and of O-2 species formed in the presence of Co(en)2+3 have been described. The catalytic properties of Co-ethylenediamine surface complexes with respect to the hydrogen peroxide decomposition reaction have been investigated and a probable mechanism has been suggested.

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.

Decomposition of hydrogen peroxide on nickel-silver two-component catalyst

1984 ◽  
Vol 49 (10) ◽  
pp. 2222-2230 ◽  
Author(s):  
Viliam Múčka ◽  
Rostislav Silber
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Properties ◽  
Silver Ions ◽  
Surface Concentration ◽  
Chloride Ions ◽  
Nickel Silver ◽  
Silver Catalysts ◽  
Physico Chemical ◽  
Low Degree ◽  
Defective Crystal

The catalytic and physico-chemical properties of low-temperature nickel-silver catalysts with nickel oxide concentrations up to 43.8% (m/m) are examined via decomposition of hydrogen peroxide in aqueous solution. The mixed catalysts prepared at 250°C are composed of partly decomposed silver carbonate or oxide and nickel carbonate or hydroxide decomposed to a low degree only and exhibiting a very defective crystal structure. The activity of these catalysts is determined by the surface concentration of silver ions, which is affected by the nickel component present. The latter also contributes to the thermal stability of the catalytic centres of the silver component, viz. the Ag+ ions. The concentration of these ions varies with the temperature of the catalyst treatment, the activity varies qualitatively in the same manner, and the system approaches the Ag-NiO composition. The catalytic centres are very susceptible to poisoning by chloride ions. A previous exposition of the catalyst to a gamma dose of 10 kGy from a 60Co source has no measurable effect on the physico-chemical properties of the system.

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