The changes in hydrodesulfurization activity, selectivity, dispersion, sulfidation, and extent of
promotion of Co(Ni)Mo catalysts were investigated when the alumina support surface is modified
by grafting 4 wt% silica. Adding SiO2 eliminates the most reactive hydroxyl groups on the
alumina surface (IR band at 3775 cm 1) decreasing the possibility of generating tetrahedral Mo
species difficult to sulfide in favor of octahedral ones capable of contributing to the sulfided active
phase. The catalysts were evaluated in the hydrodesulfurization of 4,6-dimethyldibenzothiophene.
Incorporating SiO2 to alumina increases the hydrogenation rate constant and therefore the global
hydrodesulfurization rate of 4,6-dimethyldibenzothiophene and enhances the promotion of Mo by
Co (or Ni). The global sulfidation of Ni is not affected by the addition of silica but the sulfidation
of cobalt is significantly improved. The extent of promotion of the NiMo/Al2O3 and NiMo/SiO2/
Al2O3 catalysts was greater than the one achieved in their Co-promoted counterpartsCB-168827, beca posdoctoral otorgada por CONACyT al Dr. Adolfo Romero Galarza
from DGAPA-UNAM, project PAPIIT-IN-113015. We
thank Mariela Bravo-Sanchez (Universidad de Guadalajara)
for her discussion about the XPS results, Ivan Puente
for the TEM work, and Alberto Herrera-Gómez
(CINVESTAV-Unidad Querétaro, Mexico) for providing
computer program AANALYZER version 1.2
