Abstract:
The hydrodenitrogenation of quinoline on unsupported and supported (Ni)MoS2 catalysts has been explored to study the typical reactions involved. These include hydrogenation, ring opening, and nitrogen removal via aliphatic C(sp3)-N or aromatic C(sp2)-N bond cleavage. Physicochemical and kinetic studies were combined to establish an atomistic mechanistic model. The electron rich sites at the edge of the sulfide particles are concluded to be active for the hydrogenation of the aromatic ring. The ring opening via C(sp3)-N bond cleavage proceeds on sites containing an acid –SH and a basic S2- group. In contrast, the aromatic C(sp2)-N bond cleavage is concluded to occur via a reverse Mars-van Krevelen mechanism only on accessible Mo atoms at the catalyst particle edge. Accessible Ni atoms at these sites in NiMoS are unable to catalyze this reaction.