Synthesis, Characterization, and Application in Liquid Phase Organic Oxidation of LaFe_1-xCo_xO₃ Nanoparticles

Abstract

In this study, pure and Co substituted nanosized lanthanum ferrite (LaFe_1-xCo_xO₃; x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 1) perovskites were synthesized by inorganic sol–gel route, and investigated as catalysts for styrene oxidation environmental reaction using H₂O₂ as oxidant. The effect of cobalt content on physico-chemical properties of LaFeO₃ perovskite was studied by means of XRD, FTIR and N₂ physisorption. XRD analyses revealed that a stable perovskite with orthorhombic structure up to x = 0.4 was obtained, whereas for higher cobalt content, the rhombohedral structure was formed. Furthermore, the partial replacement of Fe(III) with Co (III) cations restrained the growth of the large crystallites of LaFeO₃ (~74 nm). In the FTIR spectra, the shift of Fe–O bonds position toward higher frequencies proved the incorporation of cobalt in the perovskite structure. BET surface area values were found to be between 7 and 17 m²/g. Through the catalytic tests results, the lowest substituted catalyst exhibited a higher activity than pure LaFeO₃ while further increase of cobalt content led to a remarkable decrease in the performance of the catalyst. All catalysts converted styrene to Benzaldehyde selectively. Finally, it should be mentioned that the reaction proceeded with no leaching which confirms its heterogeneous nature.