The kinetics of reduction of nickel oxide-cerium dioxide mixed systems with hydrogen and the effect of ionizing radiation on it

1984 ◽  
Vol 49 (10) ◽  
pp. 2241-2251 ◽  
Author(s):  
Milan Pospíšil ◽  
Igor Petrecký
Keyword(s):  
Nickel Oxide ◽  
Maximum Rate ◽  
Cerium Dioxide ◽  
Effect Of Temperature ◽  
Composition Region ◽  
System Composition ◽  
Radiation Induced ◽  
Kinetics Of ◽  
Mixed Systems ◽  
Kinetics Of Reduction

The reduction with hydrogen is studied thermogravimetrically over the temperature region of 260-500 °C for nickel oxide-cerium dioxide mixed systems of various composition. The overall rate of reduction increases and the maximum rate of reduction of nickel oxide decreases with increasing cerium dioxide content as a result of two counteracting processes occurring on the reaction interface and conditioned by the presence of the finely dispersed unreducible component. The dependence of the degree of reduction α on time t obeys the relation (α + 0.3)/(1 - α) = Aekt over the entire system composition region. Previous exposition of the samples to gamma does of 100 and 500 kGy from a 60Co source or to a fast neutron dose of 400 Gy from a 252Cf source results in a decrease in the rate of reduction for region with excess nickel oxide, but as the concentration of cerium dioxide is increased, inversion of the radiation-induced effect takes place and the rate of reduction becomes higher than for the initial, unexposed samples. The effect of temperature and system composition on the phenomena under study is examined and discussed.

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.

Kinetics of reduction of nickel oxide with CO

AIChE Journal ◽  
1972 ◽  
Vol 18 (3) ◽  
pp. 506-512 ◽  
Author(s):  
J. H. Krasuk ◽  
J. M. Smith
Keyword(s):  
Nickel Oxide ◽  
Kinetics Of ◽  
Kinetics Of Reduction

ChemInform Abstract: Kinetics of Reduction of Nickel Oxide and Nickel Aluminate by Hydrogen.

ChemInform ◽  
2010 ◽  
Vol 26 (2) ◽  
pp. no-no
Author(s):  
S. SRIDHAR ◽  
D. SICHEN ◽  
S. SEETHARAMAN
Keyword(s):  
Nickel Oxide ◽  
Nickel Aluminate ◽  
Kinetics Of ◽  
Kinetics Of Reduction

The Kinetics of Reduction of Dense Synthetic Nickel Oxide in H2-N2 and H2-H2O Atmospheres

2009 ◽  
Vol 40 (1) ◽  
pp. 1-16 ◽  
Author(s):  
T. Hidayat ◽  
M.A. Rhamdhani ◽  
E. Jak ◽  
P.C. Hayes
Keyword(s):  
Nickel Oxide ◽  
Kinetics Of ◽  
Kinetics Of Reduction

Prothrombin Evaluation as Obtained by Kinetics Studies of Antigen-Antibody Reaction in a Laser Nephelometer

1984 ◽  
Vol 52 (01) ◽  
pp. 015-018 ◽  
Author(s):  
A Girolami ◽  
A Sticchi ◽  
R Melizzi ◽  
L Saggin ◽  
G Ruzza
Keyword(s):  
Liver Cirrhosis ◽  
Cirrhotic Patient ◽  
Maximum Rate ◽  
Serum Proteins ◽  
Clotting Factors ◽  
Kinetics Studies ◽  
Maximum Value ◽  
Time Required ◽  
Antigen Antibody ◽  
Kinetics Of

SummaryLaser nephelometry is a technique which allows the evaluation of the concentration of several serum proteins and clotting factors. By means of this technique it is also possible to study the kinetics of the reaction between antigen and antibody. We studied the kinetics of the reaction between prothrombin and an antiprothrombin antiserum using several prothrombins namely: Prothrombin Padua, prothrombin Molise, which are two congenital dysprothrombinemias, cirrhotic, coumarin or normal prothrombins. Different behaviors in the kinetics of the reactions were shown even when the concentration of prothrombins was about the same in all plasma tested. These differences were analyzed by means of a computer (Apple II 48 RAM) programmed to solve four unknown equations (Rodbard’s equation). From the data so obtained one can see that when voltages at the beginning and at the end of the reaction are in all cases about the same, a clear difference in the time required to reach half the maximum value of the voltage can still be demonstrated. This parameter, which is expressed in minutes, is longer in coumarin and prothrombin Molise than in controls. On the contrary it is shorter in prothrombin Padua and has about the same value of controls in the cirrhotic patient. Moreover the time at which the maximum rate is obtained is longer in coumarin and prothrombin Molise than in controls and shorter in liver cirrhosis and prothrombin Padua. In conclusion data obtained show that coumarin prothrombin behaves in a different way from cirrhotic prothrombin and also that there is a different behaviour between the two congenital dysprothrombinemias.

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