CO2 Methanation: Solvent-Free Synthesis of Nickel-Containing Catalysts from Complexes with Ethylenediamine

Abstract

CO2 methanation was studied in the presence of nickel catalysts obtained by the solid-state combustion method. Complexes with a varying number of ethylenediamine molecules in the coordination sphere of nickel were chosen as the precursors of the active component of the catalysts. Their synthesis was carried out without the use of solvents, which made it possible to avoid the stages of their separation from the solution and the utilization of waste liquids. The composition and structure of the synthesized complexes were confirmed by elemental analysis, IR spectroscopy, powder XRD and XPS methods. It was determined that their thermal decomposition in the combustion wave proceeds in multiple stages with the formation of NiO and Ni(OH)2, which are reduced to Ni0. Higher ethylenediamine content in the complex leads to a higher content of metal in the solid products of combustion. However, different ratios of oxidized and reduced forms of nickel do not affect the initial activation temperature of nickel catalysts in the presence of CO2. It was noted that, after activation, the sample obtained from [Ni(C2H8N2)2](NO3)2 exhibited the highest activity in CO2 methanation. Thus, this complex is a promising precursor for CO2 methanation catalysts, and its synthesis requires only a small amount of ethylenediamine.

Cobalt–Imidazole Complexes: Effect of Anion Nature on Thermochemical Properties

“…Moreover, their synthesis should be simple, low-waste, and without the use of expensive equipment. The simplest way is the synthesis of metal–organic compounds without solvents by mixing solid metal salts with good chelating ligands [ 5 ], for example, ball mill use [ 6 ]. However, it is difficult to achieve phase homogeneity, which reduces the yield of metal–organic compounds and requires further purification of the target product from the impurities of the reagents.…”