Study on the reduction of ilmenite-type FeTiO3 by H2

The effect of structural properties on the reduction behaviour of ilmenite-type FeTiO3 towards H2 is investigated. A systematic series of samples with different physical-chemical features is prepared using sol-gel synthesis followed by thermal treatment in reducing atmosphere. The materials are characterized with X-ray diffraction, N2 physisorption, 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscopy, while the reducibility towards H2 is evaluated by temperature-programmed reaction (H2-TPR). A minimum of 600 °C is found necessary for the formation of crystalline FeTiO3. FeTiO3 samples are completely reduced by H2 at ca. 870 °C yielding H2O, elemental Fe and TiO2. FeTiO3 formed at 600 °C with a crystallite size of 48 nm, average particle size of 44 μm and BET surface area of 6 m2/g exhibits the lowest reduction temperature in H2-TPR revealing maximum reduction rate at 780 °C. The correlation of the structural properties with the reducibility of the samples indicated that small particles and crystallite sizes as well as high BET surface areas enhance the reaction with H2. This relationship is referred to the increasing number of surface sites, which are considered crucial for the H2 chemisorption and subsequent reduction processes.