Effect of sulfidation temperature on the intrinsic activity of Co–MoS2 and Co–WS2 hydrodesulfurization catalysts

The effect of presulfidation temperature on the magnetic property, local structure, and intrinsic hydrodesulfurization activity of Co–Mo(W)–S has been studied with SiO2-supported Co–Mo and Co–W sulfide catalysts prepared by exposing presulfided MoS2/SiO2 and WS2/SiO2, respectively, to a vapor of Co(CO)3NO. A TPS study shows that complete sulfidation of Mo(W) precursors to Mo(W)S2 particles is required for the formation of Co–Mo(W)–S Type II. The intrinsic activity of Co–W–S Type II is 1.6 times as high as that of Co–Mo–S Type II. The Co K-edge EXAFS analysis of Co–Mo(W)–S confirms the formation of dinuclear Co sulfide clusters on Mo(W)S2 edges. The intrinsic activity of Co–Mo–S is correlated with the Co–S–Co antiferromagnetic interaction strength, suggesting modifications of the electronic state and local structure of Co–Mo–S by MoS2–O-support interactions, in conformity with the EXAFS analysis.