The Use of Hybrid Genetic Algorithm in the Kinetic Analysis of Thermal Decomposition of [Ni(C2H8N2)3](ClO4)2 with Overlapping Stages

This work describes the mathematical modeling of the thermal decomposition of the complex compound [Ni(En)₃](ClO₄)₂ (En = C₂H₈N₂ = ethylenediamine) in an inert atmosphere under non-isothermal conditions. This process is characterized by several simultaneous and intense stages: elimination of ethylenediamine from the nickel coordination sphere, decomposition of perchlorate anions, and explosive-like oxidation of free or bound ethylenediamine. These stages overlap and merge into a one step on the differential thermogravimetric curve. Typically, this curve is modeled as a one-stage process during kinetic analysis. In this paper, for the first time, the data from the dynamic mass-spectral thermal analysis and thermogravimetric analysis were modeled using the hybrid genetic algorithm, and the results were compared. A two-stage scheme of [Ni(En)₃](ClO₄)₂ thermolysis was proposed and the kinetic parameters for each stage were obtained. It was shown that the decomposition of [Ni(En)₃](ClO₄)₂ begins with the elimination of one molecule of ethylenediamine (stage A), then the perchlorate anions quickly decompose with the evolution of oxygen (stage B). We believe that the resulting ClO4-x- (x = 1-3), as stronger oxidizing agents, instantly start an explosive-like exothermic process of ethylenediamine oxidation (stage B).

New Solvent-Free Melting-Assisted Preparation of Energetic Compound of Nickel with Imidazole for Combustion Synthesis of Ni-Based Materials

In this work two approaches to the synthesis of energetic complex compound Ni(Im)₆(NO₃)₂ from imidazole and nicklel (II) nitrate were applied: a traditional synthesis from solution and a solvent-free melting-assisted method. According to infrared spectroscopy, X-ray diffraction, elemental and thermal analysis data, it was shown that the solvent-free melt synthesis is a faster, simpler and environmentally friendly method of Ni(Im)₆(NO₃)₂ preparation. The results show that this compound is a promising precursor for the production of nanocrystalline Ni-NiO materials by air-assisted combustion method. The combustion of this complex together with inorganic supports makes it possible to synthesize supported nickel catalysts for different catalytic processes.