Catalytic hydrotreating of heavy gasoil FCC feed on alumina-titania-supported NiMo catalysts

A series of NiMo/γ-Al₂O₃-TiO₂ catalysts were prepared and tested in the hydrotreating of heavy gasoil FCC feed in a pilot plant fixed-bed reactor. Three different methods were applied to obtain the alumina-titania mixed oxides: Impregnation of titanium butoxide over a γ-Al₂O₃ support, co-precipitation of a mixture of aluminum sulfate, sodium aluminate and titanium sulfate, and a sol-gel method using alkoxides as precursors; the titanium content was kept constant (5 wt.%). Additionally, a γ-Al₂O₃ support was also prepared as a reference. All supports were characterized by XRD, FT-IR pyridine and HRTEM. Catalysts were prepared by spraying at incipient wetness with the appropriate Ni-Mo solution. Catalytic activity results (HDS, HDM and HDA) showed marked influence of the preparation method. This behaviour is explained in terms of the differences in titania dispersion and acidity of the support.