Structural And Morphological Characterization Of The Perovskite Lafe0.2cr0.8-Xcoxo3 (X=0.0, 0.2, 0.4, 0.6, 0.8) For Selective Oxidation Of Co

Five compositions of the system LaFe0.2Cr0.8-XCoXO3 (x = 0.0, 0.2, 0.4, 0.6, 0.8) were synthesized by using a combustion technique to investigate the structural and morphological properties of doped LaCrO3 perovskite oxides. The optimal physicochemical conditions for the synthesis of the materials from citrate precursors at low temperature were studied through gravimetric and differential thermal analysis (TGA-DTA). X-ray diffraction (XRD) and electron microscopy (SEM-TEM) characterization of the calcined oxides confirmed the formation of a single perovskite-type structure in all the materials. The incorporation of cobalt into the structure was associated with an evolution from a rhombohedral R3-c to an orthorhombic Pnma 62 structure, with nanometric particle sizes and relevant surface properties. The results obtained from Raman and X-ray photoelectron spectroscopy (XPS) evidenced that the chemical composition and the of the cations were in accordance with the proposed system and the employed synthesis method. The conversion of CO and O-2 was between 83.5 and 100% for all oxides, depending on the cobalt content, and the positive effect of temperature on the conversion and the selectivity for the formation of CO2. Stability tests confirmed a stable conversion of CO and O-2, with high initial values around 96% +/- 0.97, which stabilized at 83.5% +/- 0.87 for the less reactive materials.