In this paper, NiMoO 4 powder was synthesized by the complexation method combining EDTA-Citrate. The behavior of the NiMoO 4 material in the ethyl transesterification reaction was evaluated by analyzing the acidity index under specified reaction conditions. The results showed that NiMoO 4 crystallized at 800 °C with a total mass loss of 85%, presenting a monoclinic structure, free of secondary phases, high degree of crystallinity and average crystallite size of 140 nm. The particles had heterogeneous sizes and shapes, but with well-defined contours. The increase in the mass of NiMoO 4 in the reaction medium reduced the acidity index (0.8 mgKOH.g -1 with 15 wt.%). Despite the use of the minimum molar ratio (1:3), the ethyl route being less reactive and the use of the operating temperature close to the alcohol evaporation temperature, NiMoO 4 showed promising catalytic potential in the transesterification process.

The synthesis of ceramic materials such as ferrite has been widely studied in recent years, due to their properties that make these materials have excellent applications in technology, as well as in photocatalytic processes and as catalysts. To obtain the copper ferrite phase the EDTA-Citrate complexation method was used, varying pH (5, 7 and 9), temperature (600, 800 and 1000 °C) and calcination time (2, 7 and 12 h). Composition, morphology and structural analyzes were performed by X-ray fluorescence spectroscopy, X-ray dispersive energy, scanning electron microscopy and X-ray diffraction, respectively. Crystalline phase of copper ferrite (CuFe 2 O 4 ) with tetragonal structure and secondary phase of Fe 2 O 3 and CuO was verified by XRD analysis. Regarding the chemical composition analyzes, percentage deviations of the samples and the theoretical value for copper and iron were calculated. It was obtained minimum values of 0.16 -0.08% (atomic%, EDS) and 16 -8% (atomic%, XRF) in relation to copper and iron, respectively, for the sample obtained under pH 9, calcined at 600 °C for 12 h. The variation of the synthesis condition via EDTA-Citrate directly influenced the morphology of copper ferrite, presenting agglomerated particles, pore formation, irregular spheres, and even powder sintering.