Characterization and Catalytic Properties of Ni-Fe Spinel Catalysts for Total Oxidation of Ethanol

This paper deals with the study of the reducibility of Ni-Fe spinel oxides prepared by co-precipitation and hydrothermal methods with NaOH or ammonia and their behavior in ethanol combustion. The reducibility was investigated by X-ray photoelectron spectroscopy (XPS) after pretreatment under H-2 at 400 degrees C. Depending on the synthesis method, structural properties (X-ray powder diffraction (XRD) and Raman analysis), the surface area (BET), particle size (Rietveld refinement), as well as the surface Ni/Fe atomic ratio (XPS) and the behavior upon reduction varied. The best performances were obtained for hydrothermal conditions with a total conversion achieved at similar to 300 degrees C. Ni2+ species seem to play a significant role in complete oxidation of ethanol; they were identified as the active species. A good correlation between structural, textural, reducibility and catalytic activity was established.