Solution syntheses of unsupported Co(Ni)-Mo-S hydrotreating catalysts
Résumé
Highly dispersed Ni(Co)-Mo-S sulfides were prepd. by simple room temp. soln. reactions using nickel or cobalt salts and thiomolybdate precursors in the presence of nonionic surfactants. The products were characterized by X-ray powder diffraction, sp. surface area measurements, and scanning and transmission electron microscopy. The evolution from amorphous pre-catalysts to highly dispersed sulfide catalysts during the activation step was studied by thermal anal. Extended X-ray absorption fine structure measurements were carried out to elucidate the chem. environment of the transition metals in the precursors and the sulfided catalysts. The specific catalytic activities of the Ni(Co)-Mo-S systems in the hydrodesulfurization of thiophene and 4,6-DMDBT were up to six times higher than those of com. alumina-supported systems.