Synthesis and characterization of Ce-stabilized titania for NiMo HDS catalysts

With the aim of obtaining TiO2-based catalytic supports with high surface area, pore volume and hydrothermal stability, in this work we study some of the synthesis parameters of the sol–gel preparation of Ce-modified titania, as: hydrolysis catalyst, solvent and titania precursor. The supports were used to prepare NiMo/TiO2 catalysts, which were characterized and evaluated in the thiophene HDS reaction. It was found that the use of terbutanol as solvent, phosphoric acid as hydrolysis catalyst and a low acid/alkoxide ratio (0.05) lead to enhanced areas and hydrothermal stability. For catalysts loaded with the same surface concentration of active phase, the specific HDS activity increases with surface area suggesting that the dispersion of the NiMo active phase is similar for samples with different surface areas. However, it was also found that the variations in the synthesis parameters caused changes in the degree of sulfidation of the NiMo active phase, in the amount of CUS per Mo atom, and in the temperature at which the evolution of H2S from non-stoichiometric sulfur (Sx) takes place.