Preparation and characterization of spinel-type MeFe2O4 (Me = Cu, Cd, Ni and Zn) for catalyst applications

Four kinds of spinel ferrites, MeFe2O4 (Me = Cu, Ni, Zn and Cd), were prepared by so called “selfcombustion method” using nitrates as precursors. The morphological and structural characterization of the ferrite powders have been performed with various techniques: X-ray diffraction (XRD), to determine the phase composition, SEM observations to evaluate nanostructure characteristics, EDAX spectroscopy to evaluate the chemical composition and BET analysis to determine the specific surface area. The ferrite powders have been tested catalytically in combustion reaction of three diluted gases: acetone/air, ethanol/air and methanol/air. The results revealed a pronounced decrease in the combustion temperature when Cu- and Ni-ferrites are used as catalysts. A probable cause was ascribed to multiple valences of Cu and Ni ions which favor a rapid increase in the oxygen ion species adsorbed on ferrite surface.