Effect of precursors on surface and catalytic properties of Fe/TiO2 catalysts

Titania-supported iron (5wt%) catalysts were prepared by a sol-gel method using different gelation pH and metal precursors (Fe(II) and Fe(III)). Characterization data of calcined catalysts revealed that, irrespective of the nature of the metal precursor, iron is present in all cases as ferric oxide. However, the crystalline phase exhibited by titania does depend on the metal precursor used. The catalytic activity of the catalysts, tested in the combustion of methane at atmospheric pressure, is not related to the dispersion of iron oxide. Thus, Fe3+ ions may be obtained in two extreme situations; one highly dispersed in which Fe3+ ions are placed in the titania network and another in which large Fe2O3 crystals are located on the surface of the catalyst. The former exhibits the best performance in the combustion of methane. (C) 2002 Society of Chemical Industry.