Auto-combustion synthesis, M?ssbauer study and catalytic properties of copper-manganese ferrites

摘要

Spinel ferrites with nominal composition Cu_(0.5)Mn_(0.5)Fe_2O_4 and different distribution of the ions are obtained by auto-combustion method. M?ssbauer spectroscopy, X-ray Diffraction, Thermogravimetry-Differential Scanning Calorimetry, Scanning Electron Microscopy and catalytic test in the reaction of methanol decomposition is used for characterization of synthesized materials. The spectral results evidence that the phase composition, microstructure of the synthesized materials and the cation distribution depend on the preparation conditions. Varying the pH of the initial solution microstructure, ferrite crystallite size, cation oxidation state and distribution of ions in the in the spinel structure could be controlled. The catalytic behaviour of ferrites in the reaction of methanol decomposition also depends on the pH of the initial solution. Reduction transformations of mixed ferrites accompanied with the formation of H?gg carbide χ-Fe_5C_2 were observed by the influence of the reaction medium.