Kinetics of hydrogen reduction of the Fe-Co-O system

1983 ◽  
Vol 22 (7) ◽  
pp. 516-518
Author(s):  
E. V. Ishchenko ◽  
I. V. Uvarova ◽  
V. K. Yatsimirskii
Keyword(s):  
Hydrogen Reduction ◽  
Kinetics Of

scholarly journals The influence of an external magnetic field on the dynamics of magnetite reduction with hydrogen

RSC Advances ◽  
2021 ◽  
Vol 11 (25) ◽  
pp. 15422-15427
Author(s):  
Petr A. Chernavsky ◽  
Nellie V. Kim ◽  
Victor A. Andrianov ◽  
Yurii D. Perfiliev ◽  
Alla A. Novakova ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Hydrogen Reduction ◽  
Kinetics Of

The kinetics of hydrogen reduction of magnetite was investigated in different magnetic fields.

scholarly journals The Kinetics of Isothermal Hydrogen Reduction of Nanocrystalline Fe2O3 Powder

2014 ◽  
Vol 55 (10) ◽  
pp. 1611-1617 ◽  
Author(s):  
Geon-Yong Lee ◽  
Joon-Phil Choi ◽  
Jun-Il Song ◽  
Sung-Soo Jung ◽  
Jai-Sung Lee
Keyword(s):  
Hydrogen Reduction ◽  
Kinetics Of

Kinetics of synthesizing process for obtaining iron nanopowder by chemical-metallurgical method under isothermal conditions

2021 ◽  
pp. 72-77
Author(s):  
Tien Hiep Nguyen ◽  
◽  
Van Minh Nguyen ◽  
Keyword(s):  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Reduction Process ◽  
Nitrogen Adsorption ◽  
Specific Rate ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

In this work the kinetics of synthesizing process of metallic iron nanopowder by hydrogen reduction from α-FeOOH hydroxide under isothermal conditions were studied. α-FeOOH nanopowder was prepared in advance by chemical deposition from aqueous solutions of iron nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. The hydrogen reduction process of α-FeOOH nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 390 to 470 °C. The study of the crystal structure and composition of the powders was performed by X-ray phase analysis. The specific surface area S of the samples was measured using BET method by low-temperature nitrogen adsorption. The average particle size D of powders was determined via the measured S value. The size characteristics and morphology of the particles were investigated by transmission and scanning electron microscopes. The calculation of the kinetic parameters of the hydrogen reduction process of α-FeOOH under isothermal conditions was carried out by the Gray-Weddington model and Arrhenius equation. It is shown that the rate constant of reduction at 470 °C is approximately 2.2 times higher than in the case at 390 °C. The effective activation energy of synthesizing process of iron nanopowder by hydrogen reduction from α-FeOOH was ~38 kJ/mol, which indicates a mixed reaction mode. In this case, the kinetics overall process is limited by both the kinetics of the chemical reaction and the kinetics of diffusion, respectively, an expedient way to accelerate the process by increasing the temperature or eliminate the diffusion layer of the reduction product by intensive mixing. It is show that Fe nanoparticles obtained by hydrogen reduction of its hydroxide at 410 °C, corresponding to the maximum specific rate of the reduction process, are mainly irregular in shape, evenly distributed, the size of which ranges from several dozens to 100 nm with an average value of 75 nm.

Study on the kinetics of process for obtaining cobalt nanopowder by hydrogen reduction under isothermal conditions

2021 ◽  
Vol 1 (1) ◽  
pp. 49-56
Author(s):  
Hieр Nguyen Tien
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

The kinetics of metallic cobalt nanopowder synthesizing by hydrogen reduction from Co(OH)2 nanopowder under isothermal conditions were studied. Co(OH)2 nanopowder was prepared in advance by chemical deposition from aqueous solutions of Co(NO3)2 cobalt nitrate (10 wt.%) and NaOH alkali (10 wt.%) at room temperature, pH = 9 under continuous stirring. The hydrogen reduction of Co(OH)2 nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 270 to 310 °C. The crystal structure and composition of powders was studied by X-ray phase analysis. The specific surface area of samples was measured using the BET method by low-temperature nitrogen adsorption. The average particle size of powders was determined by the measured specific surface area. Particles size characteristics and morphology were investigated by transmission and scanning electron microscopes. Kinetic parameters of Co(OH)2 hydrogen reduction under isothermal conditions were calculated using the Gray–Weddington model and Arrhenius equation. It was found that the rate constant of reduction at t = 310 °C is approximately 1.93 times higher than at 270 °C, so the process accelerates by 1.58 times for 40 min of reduction. The activation energy of cobalt nanopowder synthesizing from Co(OH)2 by hydrogen reduction is ~40 kJ/mol, which indicates a mixed reaction mode. It was shown that cobalt nanoparticles obtained by the hydrogen reduction of its hydroxide at 280 °C are aggregates of equiaxed particles up to 100 nm in size where individual particles are connected to several neighboring particles by contact isthmuses.

Kinetics of Lime-Enhanced Hydrogen Reduction of Solid Nickel Sulphide

1992 ◽  
Vol 10 (1) ◽  
pp. 109-120 ◽  
Author(s):  
RAJESH PATHAK ◽  
T. R. MANKHAND ◽  
J. S. KACHHAWAHA ◽  
P. M. PRASAD
Keyword(s):  
Hydrogen Reduction ◽  
Nickel Sulphide ◽  
Solid Nickel ◽  
Kinetics Of

Kinetics of catalytic hydrogen reduction of SiCl4 in the presence of nickel chloride

2012 ◽  
Vol 49 (1) ◽  
pp. 1-5 ◽  
Author(s):  
A. V. Vorotyntsev ◽  
G. M. Mochalov ◽  
V. M. Vorotyntsev
Keyword(s):  
Hydrogen Reduction ◽  
Nickel Chloride ◽  
Catalytic Hydrogen ◽  
Kinetics Of

scholarly journals Kinetics of NiO and NiCl2Hydrogen Reduction as Precursors and Properties of Produced Ni/Al2O3and Ni-Pd/Al2O3Catalysts

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Miroslav Sokić ◽  
Željko Kamberović ◽  
Vesna Nikolić ◽  
Branislav Marković ◽  
Marija Korać ◽  
...  
Keyword(s):  
Metal Content ◽  
Hydrogen Reduction ◽  
Effect Of Temperature ◽  
Synthesis Process ◽  
Reduction Temperature ◽  
Time Intervals ◽  
Reduction Processes ◽  
Calcination Step ◽  
Before And After ◽  
Kinetics Of

The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3catalysts. The effect of temperature and time on NiO and NiCl2reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K.

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