Effect of chlorine precursor in surface and catalytic properties of Fe/TiO2 catalysts

Titania-supported iron (1wt%) catalysts were prepared by the sol-gel method using different gelation pH (3 and 9), metal precursors (FeCl2 and FeCl3) and calcination temperatures (873 and 1073K). Characterization data of calcined catalysts revealed that in all samples the dominant iron species is Fe 31 and the crystalline phase of the TiO2 substrate depends on the gelation pH and the metal precursor used. It was found that in the Fe/TiO2 ex-FeCl3 samples an important part of the iron ions became inserted in titania lattice, which makes the anatase phase stable even at high calcination temperatures. The solids were tested in the combustion of methane under stoichiometric conditions at atmospheric pressure. It was observed that the Fe/TiO2 ex-FeCl2 sample displays the highest activity. This behaviour is explained on the basis of the highest fraction of iron oxide deposited on the external surface of the catalyst particles.