Highly dispersed CoMoS phase on titania nanotubes as efficient HDS catalysts

Nanotubular titania (NT) to be used as support for CoMo-based hydrodesulfurization (HDS) catalyst was synthesized and characterized by various techniques. NT annealed at 400 °C (under nitrogen) was constituted by nanotubes of ∼5.5 nm (internal diameter) and retained 236 m2/g of surface area. Mo at 3 atoms/nm2 (nominal loading) and cobalt at Co/(Co + Mo) = 0.3 were impregnated under nearly neutral, acidic or basic media. By XPS analyses of NT-supported sulfided catalysts, highly dispersed MoS2 particles of low stacking degree (1–2 slabs) aligned along the nanotubes were observed by HR-TEM in all sulfided materials. The CoMo catalysts supported on nanostructured titania had dibenzothiophene (DBT) HDS activity (in pseudo first order kinetic constant basis) values ∼1.35 and ∼1.7 times (Mo impregnated under near neutral and basic media, respectively) higher to that of a commercial reference with alumina carrier. According to shifts to higher binding energy of the Co 2p peak corresponding to sulfided cobalt (as determined by XPS), MoS2 dispersed on NT support could be efficiently promoted by Co (“CoMoS” phase formation), opening the possibility of developing new highly active HDS catalysts.