Comparison of catalytic properties of NiMoAl2O3 with NiMo supported on Al-, Ti-pillared clays in HDS of residual oils Original Research Article

NiMo supported on Al- and Ti-PILCs catalysts were prepared and tested in the hydrotreating of residual atmospheric gasoil (375°C cut), from Maya type crude (3.7 wt.-% sulfur, 11 wt.-% asphaltenes, 21.5 wt.-% aromatics, 16 wt.-% polars). At 400°C NiMoTi-PILC lowers the asphaltene fraction by 77.2 wt.-%, while aromatics decrease by 53.5 wt.-% and polar fractions diminishes by 43.8 wt.-%. This is about 4.5, 9.3 and 22.5 wt.-% higher than NiMoAl2O3 reference catalysts. The relative HDS rates for NiMoTi-PILC are 40.4, 22.8 and 18% HDS/m2 for sulfur removal in the asphaltene, polar and aromatics fractions, respectively. In the same sequence NiMoAl2O3 catalysts give 11.4, 1.6 and 19.6% HDS/m2. The X-ray microanalysis of clay-supported catalysts, in a single plate mode, after reaction and regeneration, indicates significant variations in the metal and sulfur content on the flakes faces with respect to the edges, which may correlate with catalytic active sites for HDS. After regeneration by means of THF solvents, refluxing and calcination in air at 380 C, both the physical and catalytic properties of NiMoTi-PILC and NiMoAl2O3 were recovered. The active metal redistribution of Ni on clay flake edges seemed responsible for enhancing the activity after regeneration.