A series of alumina-aluminum borates (AAB) with various boria contents were prepared by a coprecipitation technique. They were characterized with respect to surface area, pore volume, and pore size distribution. The temperature-programmed-reduction (TPR) method was used to monitor molybdenum oxide-support interaction. The results showed that both the T-max and hydrogen consumption of low-temperature-reduction peak increase with increasing B2O3 content. Hydrodesulfurization of heavy residue oils over NiMo/AAB catalysts was carried out in a trickle bed reactor at 663 K and 7.6 MPa. The results revealed that these catalysts are much more active than the conventional NiMo/Al2O3 catalysts. The dispersion of active sulfide phase as well as the hydrogenation ability of NiMo/Al2O3 catalyst is increased by the incorporation of adequate boria content. An optimum B2O3 content which gives the highest activity was found in the vicinity of 4 wt %.
