This work reports the synthesis of Ni-clay catalysts by impregnation of Al-pillared saponite with various
Ni salts, using several Ni loadings. The catalysts were characterized by X-ray diffraction, infrared spectroscopy,
thermogravimetric and differential thermal analysis, nitrogen adsorption, temperature-programmed
reduction studies, and ultraviolet–visible spectroscopy. All the solids displayed good
structural properties. FTIR spectroscopy confirmed the total removal of the anionic precursors after calcination
of the solids at 500 C. The presence of NiO and NiAl2O4 in the nickel particles formed on the surface
of the solids was demonstrated. Deconvolution of TPR curves allowed to identify three Ni-reduction
effects, their temperature and relative intensity depended on the preparation of each sample. The catalytic
behaviour of the solids for (Z)-cyclooctene epoxidation and cyclohexane oxidation by either iodosylbenzene
(a model oxidant) or hydrogen peroxide (a clean oxidant) was studied. In the case of the
epoxidation reactions, there was 100% selectivity for the epoxide. As for cyclohexane oxidation, only
cyclohexanone was formed, whereas no cyclohexanol was detected. The use of radical scavengers indicated
that the high-valent oxo-nickel species is responsible for the oxygen transfer between the oxidant
and the substrates.