One pot preparation of NiO/ZrO₂ sulfated catalysts and its evaluation for the isobutene oligomerization

The synthesis of NiO/ZrO₂ sulfated catalysts prepared by the one pot method (sol-gel) is reported. Specific surface areas comprised between 52 and 108 m²/g were obtained. XRD patterns showed the presence of monoclinic and tetragonal zirconia phases. FTIR-pyridine absorption spectra show the presence of Lewis and Brönsted sites in sulfated zirconia but only Lewis sites in nickel zirconia sulfated catalysts. A good correlation between the amount of adsorbed pyridine and the catalytic activity for the isopropanol dehydration was observed. However, an opposite effect was observed for the isobutene oligomerization, where the catalysts with the lower acidity showed the higher activity. The role of Ni⁺² diminishing the deactivation rate forming π-allylic bonds with the olefins is discussed.