EFFECT OF METAL CONTENT ON THE ACIDITY OF SUPPORTED NICKEL-MOLYDATE CATALYST.

The acid properties of nickel promoted and unpromoted MoO//3/Al//2O//3 catalysts were studied by ammonia adsorption, n-butylamine titration, and the hydrodesulphurization reaction of thiophene. The incorporation of molybdenum to the support and of nickel to supported MoO//3 were found to produce increases in acidity, however the latter increase is the result of an increment of intermediate strength acid sites, while the number of strong sites is diminished. It is suggested that the promoter inhibits the initial deactivation of the catalyst by eliminating strong Bronsted sites. Both strong Lewis and strong Bronsted sites are supposed to be active for hydrodesulphurization. The former sites are mainly present in the sulphided promoted catalyst, and the latter in the oxidic unpromoted catalyst.