Influence of Support Acidity of NiMo Sulfide Catalysts for Hydrogenation and Hydrocracking of Tetralin and Its Reaction Intermediates

Aromatic saturation is an important reaction for improving the cetane number of diesel streams. NiMo sulfide catalysts supported on alumina (Alu), silica–alumina (Si–Al), and alumina-Y zeolite (AluZ) were prepared with similar dispersions and variable acidities. These catalysts were tested in the hydroconversion of tetralin, indan, decalins, and alkylbenzenes to evaluate the effect of the support acidity in the overall activity and the distribution of products. NiMo/Alu generated essentially hydrogenated products while the presence of an acid component on the support increased not only isomerization and cracking reactions but also hydrogenated compounds formation, especially on tetralin, indan, and butylbenzene hydroconversions over NiMo/AluZ catalyst. The better hydrogenation activity of NiMo/AluZ for these reactions was associated with the presence of strong acid sites that contribute to creating protonated species which would migrate to the sulfide phase. Such species would be easier to hydrogenate due to the lower stability of the aromatic ring

Effects of Phosphorus Content on Simultaneous Ultradeep HDS and HDN Reactions over NiMoP/Alumina Catalysts

The effects of phosphorus content on competitive hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and hydrodenitrogenation (HDN) of quinoline (Q) over NiMo catalysts were evaluated. Reactions were carried out in a trickle-bed high-pressure flow microreactor. HDS of 4,6-DMDBT was strongly inhibited at Q concentrations of 90 ppmw N, mostly hydrogenation (HYD) route in HDS, suggesting that 4,6-DMDBT and Q compete for the same hydrogenation active sites, which was confirmed by the products’ distribution in HDN reactions. Morphology and nature of active sites promoted by phosphorus addition led to different activity performance on competitive HDS and HDN reactions, as evidenced by TOF values. At low concentrations of Q, promoted catalysts maintained activity for both HDS and HDN. High Q levels (above 90 ppmw N) decreased HDS and HDN activity due to stronger inhibition of catalysts. The addition of 1 wt % of phosphorus showed superior activity, attributed to a combination of better dispersed NiMoS active sites and Brønsted acidity