Effets of Cobalt Oxide-Iron Oxide Ratios on the Catalytic Activity of Cobalt Ferrite Spinel Catalysts

Abstract
The cobalt ferrite spinels Co_xFe_3-xO₄ (0.6<x<2.4) have been prepared by coprecipitation. The structures of the catalysts were characterized by DTA, X-ray diffraction, surface area and electrical conductivity measurements. The catalytic decomposition of isopropanol was carried out at 325°C using a flow system. The results obtained revealed that the activity and selectivity of the catalysts are strongly affected by the structure of the ferrite spinel formed as a result of the solid - solid interaction between Fe₂O₃ and Co₃O₄. The normal spinel formed at (x = 1) gives low activity and low selectivity in comparison with the spinels deviated from the stoichiometry. Additionally, a little change in catalytic behaviour observed on increasing the calcination temperature from 400° to 600°C. Correlations between the composition, electronic and catalytic properties of the catalysts are reported.