ROLE OF NICKEL IN HYDRODESULPHURISATION CATALYSTS.

The acidity and activity of promoted (with NiO) and unpromoted MoO//3/Al//2O//3 catalysts were studied by ammonia adsorption, titration using acid/base color indicators, and thiophene hydrodesulphurization. The incorporation of nickel into supported MoO//3 produced significant changes in activity, which was attributed to changes in the number and strength of the acid sites. Specifically, the nickel decreased the concentration of highly acid sites and increased the number of sites with intermediate acidity in the oxide catalyst. Carbon and sulphur analyses, as well as acid site concentration of used catalysts, suggest that this behavior may be associated with modifications brought about by nickel on MoS//2 crystallite growth and on deactivation by carbon deposition.