STUDY ON PROMOTION OF COBALT AND RUTHENIUM IN REDUCED CATALYSTS FOR HYDRODESULFURIZATION BY IR-SPECTROSCOPY AND CHEMISORPTION

IR-spectroscopy and chemisorption in accompanying with CO, NO, H-2, O-2 as probe molecules have been used to elucidate the function of cobalt and ruthenium in the reduced Co-Mo/Al2O3, Ru-Mo/Al2O3, Ru-Co-Mo/Al2O3 catalysts. It is found, the location of cobalt has a partial block effect on Mo sites in its low oxidation state for adsorbing CO, NO, H-2, O-2 probes on reduced Co-Mo/Al2O3 catalysts, the intensities of CO and NO bands on Co sites are increased and the NO bands are shifted to the higher freqency side by about 20 cm(-1) in comparing with that on Co/Al2O3 catalysts. In contrast to cobalt, uptake of CO, NO, H-2, O-2 probes are increased evidently on the Mo sitesin the coordination unsaturated state with the addition of ruthenium in the Ru-Mo/Al2O3 and Ru-Co-Mo/Al2O3 catalysts. It is suggested that ruthenium can promote the dissociation of hydrogen and the spilling of active hydrogen over Mo sites, which will be beneficial to the formation of more coordination unsaturated Mo sites