Strong metal-support interaction in <font>Ni</font>/<font>TiO</font>₂ catalysts: in situ EXAFS and related studies

In situ EXAFS and X-ray diffraction investigations of Ni/TiO 2 catalysts show that NiTiO 3 is formed as an intermediate during calcination of catalyst precursors prepared by the wet-impregnation method; the intermediate is not formed when ion-exchange method is used for the preparation. On hydrogen reduction, NiTiO 3 gives rise to Ni particles dispersed in the TiO 2 (rutile) matrix. The occurrence of the anatase-rutile transformation of the TiO 2 support, the formation and subsequent decomposition/reduction of NiTiO 3 as well as the unique interface properties of the Ni particles are all factors of importance in giving rise to metal-support interaction. Active TiO 2 (anatase) prepared from gel route gives an additional species involving Ni 3+ .