Simultaneous hydrodenitrogenation and hydrodesulfurization on unsupported Ni-Mo-W sulfides

The catalytic properties of unsupported Ni-Mo-W sulfides (composites of Ni-Mo(W)S₂ mixed sulfides and Ni₃S₂) obtained from precursors synthesized via co-precipitation, hydrothermal, and thiosalt decomposition were explored for hydrodenitrogenation (HDN) of o-propylaniline or quinoline in presence and absence of dibenzothiophene undergoing hydrodesulfurization (HDS). The conversion rates varied with the reacting substrate and were related to specific catalyst properties such as morphology, texture, surface and composition. For the HDN of o-propylaniline and the HDS of dibenzothiophene in presence of o-propylaniline, high concentrations of coordinatively unsaturated cationic sites (as characterized by NO adsorption) and the specific surface areas determined the rates of reaction. For the HDN of quinoline and the HDS of dibenzothiophene in the presence of quinoline, the high hydrogenation activity of tungsten sulfide and length of the slabs was found to be more important than in the cases with o-propylaniline. Overall, the activity of unsupported catalysts relates to the size of sulfide slabs provided that Ni is present at the perimeter of the slabs.