Effect of H₂S and NH₃ on Aromatics Hydrogenation Over Sulfided Pt and NiMo Based Hydrotreating Catalysts

The influence of H 2 S or NH 3 partial pressure on the rate of toluene hydrogenation over sulfided NiMo and Pt catalysts has been investigated. H 2 S is an inhibitor for both catalysts and its negative effect is totally reversible. NH 3 is also a contaminant, however, its negative effect is only partially reversible. At very low H 2 S and NH 3 partial pressure and in the same operating conditions, the Pt catalyst is always more active per gram of metal than the NiMo catalyst. The NiMo sulfide catalyst is more sensitive to NH 3 than to H 2 S whereas the Pt catalyst is more sensitive to H 2 S than to NH 3 .