Alumina-Titania Nanofibers, Synthesis by a pH-Swing Method

In an Al2O3-TiO2 mixed oxide system, the incorporation of TiO2 to alumina is known to increase the acidity of the resulting mixed oxide; depending strongly on the preparation method and the titania concentration. When using TiO2 as a support of NiMo catalysts, initial catalytic activity in hydrodesulfurization reactions is much higher than that on catalysts based on pure alumina. One of the main inconveniences of using TiO2 as a catalyst support is its low specific surface area (50-60 m/g) and pore volume (~0.3 cm/g). One approach to overcome these textural disadvantages is to disperse TiO2 on a given alumina support. Therefore, the use of alumina-titania as a catalyst support is a good alternative to improve hydrotreating catalysts performance, as long as high TiO2 dispersions are achieved . To our knowledge, studies on fibrillar alumina-titania mixed oxides have not been reported. The importance of fibrillar alumina morphology lies on its inter-fibrillar pores, which favor the diffusion and eventual transformation of huge refractory asphaltene and Ni, V porfirinic molecules contained in oil residua, which represent the most difficult hydrocarbons to transform in oil hydrotreatment reactions, and contribute enormously to deactivation of catalysts active sites.