Decomposition of hydrogen peroxide on nickel oxide-cerium dioxide catalysts and the effect of ionizing radiation on them

1984 ◽  
Vol 49 (10) ◽  
pp. 2231-2240 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Heat Treatment ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Nickel Oxide ◽  
Cerium Dioxide ◽  
Catalyst Activity ◽  
Fast Neutrons ◽  
Entire Region ◽  
Catalyst Composition ◽  
Cerium Iv Ammonium Nitrate

Physical characteristics of nickel oxide-cerium dioxide catalysts and their catalytic activity in the decomposition of hydrogen peroxide were studied over the entire region of catalyst composition. The systems under study, prepared from cerium(III) nitrate, were compared with those prepared previously from cerium(IV) ammonium nitrate, and the properties of the catalysts were found to be affected considerably by the nature of the precursor used. Nevertheless, in spite of the differences the catalytic reaction on the catalysts of the two series seems to proceed on catalytic centres of the same kind, the extent to which the centres operate being dependent on the catalyst composition. The changes in the catalyst activity brought about by sample ageing, heat treatment, or previous exposition to gamma or beta rays or fast neutrons can be accounted for, in terms of the bivalent catalytic centres concept, by interaction of the catalytic centres with oxygen or the radiation applied.

Decomposition of hydrogen peroxide on cerium dioxide-nickel oxide two-component catalysts and the effect of ionizing radiation on them

1984 ◽  
Vol 49 (1) ◽  
pp. 14-24 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Heat Treatment ◽  
Hydrogen Peroxide ◽  
Ionizing Radiation ◽  
Nickel Oxide ◽  
Cerium Dioxide ◽  
Catalytic Properties ◽  
Specific Activity ◽  
Ion Pairs ◽  
Composition Region ◽  
Two Component

Some physical and catalytic properties of cerium dioxide-nickel oxide two-component catalysts have been studied over the entire composition region, employing the decomposition of hydrogen peroxide in aqueous solution as a model catalytic process. The two oxides have been found to affect each other, particularly for NiO contents of 9.1 and 96.7 mol%; the mutual influencing, the nature of which in the conditions applied remains unaffected by heat treatment of the sample or by its exposition to ionizing radiation, is manifested by the nonmonotonic dependences of the oxidation power and of the specific activity of the catalysts on their composition. This can be interpreted in terms of the concept of bivalent catalytic centres, assuming that for nickel oxide the centres consist of Ni2+-Ni3+ ion pairs, for cerium dioxide they consist of Ce3+-Ce4+ ion pairs, and that in the region of the mutual influencing , Ni2+-Ce4+ ion pairs play a major role. Within the scope of this concept, the increase in the oxidation power of all the catalysts in question and a simultaneously decrease in the specific activity of the pure nickeloxide exposed to ionizing radiation can be explained in terms of the ionization effect.

Decomposition of hydrogen peroxide on a mixed NiO-MgO catalyst and the effect of ionizing radiation on the catalyst

1979 ◽  
Vol 44 (4) ◽  
pp. 1003-1014 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Heat Treatment ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Room Temperature ◽  
View Point ◽  
Composition Region ◽  
Catalyst Composition ◽  
Chemisorbed Oxygen ◽  
Two Component ◽  
Nonlinear Relation

The decomposition of hydrogen peroxide in aqueous solution was studied on the NiO-MgO two-component catalyst, which occurs as solid solution in the whole composition region (0-100% component fractions). The results indicate that the mutual influencing of the two oxides shows up predominantly in the different amount of oxygen chemisorbed on the surface, which may be due to the different particle size of the various catalysts. The catalytic activity of the samples, being proportional to the amount of chemisorbed oxygen, is thus in a nonlinear relation to the catalyst composition. From the view point of the concept of bivalent catalytic centres, the catalytic activity can be thus assumed to be controlled by the concentration of the minor donor reaction centres constituted by the Ni3+ ions. In addition, catalytic centres of another kind, probably charge one, take part in the catalytic activity of the system in question. The two kinds of catalytic centres can be affected by the temperature of calcination during the preparation of the oxides, their heat treatment, and also by gamma-irradiation of the system. The equilibrium state of the two kinds of catalytic centres is attained rather slowly at room temperature.

Decomposition of hydrogen peroxide on a two-component NiO-CdO catalyst and the effect of ionizing radiation on its catalytic properties

1979 ◽  
Vol 44 (4) ◽  
pp. 1015-1022 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Nickel Oxide ◽  
Catalytic Properties ◽  
Cadmium Oxide ◽  
Chemisorb Oxygen ◽  
Composition Region ◽  
Chemisorbed Oxygen ◽  
Two Component

The catalytic properties of two-component catalyst nickel oxide-cadmium oxide with the proportions of the components covering the whole composition region 0-100% were examined by studying the decomposition of hydrogen peroxide in aqueous solution on it. In the range 0-25 mol.% CdO, cadmium oxide is found to affect infavourably the ability of nickel oxide to chemisorb oxygen. The amount of the chemisorbed oxygen increases several times on gamma irradiation of the samples. The effect of cadmium oxide on the catalytic activity of the system shows up in fresh samples only indirectly via the changed amount of the oxygen chemisorbed. In older samples the initial catalytic activity of the system is changed, which can be explained based on the concept of bivalent catalytic centres in terms of the co-action of the catalytic centres of the two oxides, which are in equilibrium. The irradiation of the system under study speeds up the processes leading to the establishing of this equilibrium which is thermally very stable, and results in a substantial increase of the catalytic activity of the samples investigated.

scholarly journals SYNTHESIS OF COMPLEX OXIDE COMPOSITIONS OF COBALT–MANGANESE AND CERIUM–ZIRCONIUM AND THEIR CATALYTIC ACTIVITY IN THE DECOMPOSITION OF HYDROGEN PEROXIDE

2019 ◽  
Vol 85 (11) ◽  
pp. 15-27
Author(s):  
Yuliia Pohorenko ◽  
Anatoliy Omel’chuk ◽  
Olexandr Ivanenko ◽  
Tamara Pavlenko
Keyword(s):  
Heat Treatment ◽  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Average Particle Size ◽  
Complex Oxide ◽  
Ammonia Solution ◽  
Average Particle ◽  
Zirconium Oxides ◽  
Co Precipitation

Cobalt oxides and/or manganese and their com-position based on cerium and zirconium oxides (CeO2 : ZrO2 = 1:1 mol.%) with a content of up to 20 wt. % are synthesized. Samples of both individual oxides and complex oxide compositions were prepared by precipitation from solutions of am-monia (room temperature) or hexamethylenetet-ramine (80–90 °C) followed by heat treatment. Results of DTA show, that due to the calcination at 400 ° C (2 h), the obtained samples lose 17–22 wt. % corresponding to 2–3.8 molecules of water. According to the X-ray powder analysis, initially are formed hydroxide compounds of cobalt (CoO· xH2O) and manganese (MnO2·yН2О), which, after being heated at 400 °C for 2 hours, are converted into mixed oxides from the composition of Co3O4 and Mn3O4. The average particle size calculated by the Sherer equation is 18–30 nm. In the study of catalytic activity on the example of the reaction of the hydrogen peroxide decomposition, it was found that the obtained samples from the solution of GMTA show a greater ability to catalytically decompose hydrogen peroxide compared to samples obtained from the ammonia solution. In this case, the catalytic activity of dried samples is twice as high as roasted, regardless of the method of obtaining. Samples of oxide compo-sitions with deposited 5–10 wt. % of Ce–Zr oxides (1:1) exhibit the highest ability to decompose H2O2. In this case, samples of compositions obtained from the solution of GMTA, have a prolonged catalytic action, and when precipitation in the solution of ammonia, the reaction takes place quite actively during 4–5 days. Compositions formed from co-deposited or mechanically mixed hydroxocompounds of cobalt and manganese with 5 wt. % of CeO2–ZrO2 (1:1) deposited on them have different catalytic activity. In the case of mechanically mixed, it is 30% lower and with subsequent calcination at 400 °C, it is reduced by almost half, and with co-precipitation, the activity is quite high and does not change with heat treatment. In the case of obtaining samples of Co–Mn with Ce–Zr (1:1) deposited on them in excess of 10 wt. % the catalytic activity of the samples dried at 80 °C is equal to the activity of the co-deposited hydroxocompounds of cobalt and manganese and  the  calcination  at  400  °C  it  reduces  it by  30 %. The best ability for catalysis was found in samples CoO·xH2O + 5 wt. % MnO2·yН2О, СоO×хН2О + 10 wt. % CeO2:ZrO2 and СоO×хН2О–MnO2×yН2О, precipitated with the GMTA solution and dried at 80 °C. The besser catalytic properties revealed a sample of СоО×хН2О + 10 wt. % CeO2:ZrO2, which with-out stirring is capable of decomposing 1.2–1.4 dm3/g of hydrogen peroxide with a rapid reaction and in the experiment the volume of H2O2 reacted was 3.4 dm3/g.

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.

Hydrogen peroxide decomposition on a two-component NiO-Fe2O3 catalyst

1986 ◽  
Vol 51 (9) ◽  
pp. 1874-1882 ◽  
Author(s):  
Viliam Múčka
Keyword(s):  
Catalytic Activity ◽  
Preparation Procedure ◽  
Fast Neutrons ◽  
Catalyst Composition ◽  
Catalyst Metal ◽  
Peroxide Decomposition ◽  
Determining Factors ◽  
Two Component ◽  
Different Content ◽  
The Given

Some physical and catalytic properties of the two-component nickel oxide-ferric oxide catalysts were studied using samples with different content of both components, covering the whole concentration range from 0 to 100% of one of the components. It was proved that these properties depend strongly on the preparation procedure of the catalyst of the desired composition and on the catalyst composition for the given preparation procedure; moreover, it was proved that the phase composition of the contact catalyst is not decisive for the catalytic activity of the given system. It seems probable that the valence state of the catalyst metal ions and their ability to form the reaction catalytic centers are the rate-determining factors. The results obtained lead at the same time to the assumption that these parameters change substantially with the catalyst composition. No changes of the catalytic activity were observed for catalysts irradiated by fast neutrons or accelerated electrons.

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