COMPARISON OF SOME CATALYTIC, STRUCTURAL AND TEXTURAL PROPERTIES OF UNSUPPORTED MOS2 AND WS2 HYDRODESULFURIZATION CATALYSTS PROMOTED BY GROUP-VIII METALS

We compare fully sulfided unsupported systems active in hydrodesulfurization and related reactions, namely FeMo, CoMo, NiMo, CoW and NiW. The results concerning FeMo and CoW are new; for the other systems, previously published data are used. The addition of a small amount of Group VIII metal (atomic proportion r = VIII/(VIB + VIII) ≈ 0.01 -0.02) brings about a marked decrease in the specific surface area of Group VIB metal sulfides; an increase is observed for higher values. Atr = 0.01 -0.02, MoS2 and WS2 have a better crystallinity. Catalytic activities (per unit surface area) under 30 bar pressure in the hydrogenolysis of thiophene are higher, by a factor of 1.7 - 10, forr = 0.25 than for r = 0.01 - 0.02. Except for CoMo, the same trend is observed for the hydrogenation of cyclohexene. In the range where the maximum synergy between the active sulfides is observed, MoS2 shows comparable activity in the hydrogenolysis of thiophene, but WS2 has a higher hydrogenating activity. Both systems show essentially the same sensitivity to the Group VIII promotors. The promoting effect of Ni in hydrogenolysis and hydrogenation is substantially higher than that of Fe or Co. © 1979.