Characterization of Promotions of Cobalt and Ruthenium in Sulfided Catalysis for Hydrodesulfurization

Temperature programmed reduction and volumetric chemisorption of O-2, H-2 and CO have been used to provide insight into the functions of cobalt and ruthenium in a series of sulfided Co-Mo/Al2O3, Ru-Mo/Al2O3, Ru-Co-Mo/Al2O3 catalysts. Cobalt interacted with molybdenum to form a stable species, i.e. CoMoS phase, which decreased the amount of oxygen chemisorption and increased uptake of CO on the Co-Mo/Al2O3 catalyst. Ru promotion is found to cause reduction temperature of Mo sites shifting to lower temperature and increase obviousely the amounts of O-2 and H-2 adsorbed on Mo sites. The function of ruthenium is explained by a concept of hydrogen spillover from Ru centers to Mo sites.