Perovskite-type oxides synthesised by reactive grinding: Part III. Kinetics of n-hexane oxidation over LaCo(1−x)FexO3

The catalytic properties in the n-hexane oxidation reaction of five nanocrystalline1Nanocrystalline perovskites are available commercially from Nanox Inc., 335 St. Joseph E., Qué. (QC), Canada G1K 3B3. (1−x)FexO3 perovskites prepared by mechanosynthesis were studied. The characterisation of such samples was reported in Part I of this contribution. One of the advantages of this mechanosynthesis technique stems from the low preparation temperature, which allows to stabilise high surface area materials. t I, the unusual properties of these new materials were illustrated for LaCoO3 and LaCo(1−x)FexO3 perovskites [1]. It was shown that controlling the calcination conditions allows to tailor the surface properties of these materials. In Part II, a preliminary account of the catalytic behaviour of such catalysts in n-hexane oxidation was reported [2]. In the present contribution, the fine control of the nature and the concentration of the various sites active in redox catalysis is demonstrated through a kinetic study of the total oxidation of n-hexane by oxygen. The roles of two oxygen species O2− and O−, respectively, associated with α and β oxygens are discussed.