Investigation of the Process of Synthesizing Nanosized Nickel Powders by Hydrogen Reduction Under Nonisothermal Conditions

We study the kinetic characteristics and properties of the product of the process of synthesizing nickel nanopowders by the hydrogen reduction of Ni(OH)₂ hydroxide compound under nonisothermal conditions. It is shown that the process of hydrogen reduction of the nanopowder of Ni(OH)₂ hydroxide takes place within the temperature range 210–300°C with the maximal specific rate equal to 9.44·10⁻⁸ kg/sec recorded at a temperature of 285°C. The activation energy of the process of reduction of Ni(OH)₂ nanopowder under nonisothermal conditions was estimated as ≈ 54 kJ/mole, which confirms the kinetic conditions of limiting of the process. It is shown that the elevation of temperature up to 285°C enables us to efficiently increase the rate of the total process of hydrogen reduction of Ni(OH)₂ nanopowder (with guaranteeing high quality of the products of reduction). The obtained Ni nanoparticles mainly have round shapes and the sizes from ten to several tens of nanometers with a mean value of 50 nm.