Effect of TiO2 content and method of titania–silica preparation on the nature of oxidic nickel phases and their activity in aromatic hydrogenation

Ni catalysts (5 wt.% of Ni) supported on titania–silica were studied. The aim of the study was to examine how the TiO2 (10, 25 and 50 wt.%) content influences the nature of oxidic nickel species on titania–silica supports which were prepared in the following mode: (i) by deposition of TiO2 on the silica surface via hydrolysis of titanium isopropoxide or via hydrolysis of titanium tetrachloride, and (ii) by sol–gel method. Titania distribution in the titania–silica support depends on the method of support preparation and influences the reducibility and distribution of nickel oxide; as the quantity of titanium increases, so does the quantity of nickel. The results indicate that the deposition of TiO2 on the silica surface via hydrolysis of titanium isopropoxide (TiO2/SiO2) improves the hydrogenation activity of nickel catalysts. The use of TiPOT for the preparation of TiO2/SiO2 increases the reducibility of nickel oxide, as well as the acidity and specific surface area of the catalyst.