Intrinsic catalytic activity of SiO2-supported Co-Mo and Co-W sulfide catalysts for the hydrodesulfurization of thiophene

SiO2-supported Co-Mo and Co-W sulfide catalysts with varying Mo(W) content were prepared from Mo(W)S2/SiO2 presulfided at 673-873 K with a CVD technique using Co(CO)3NO as a precursor to Co sulfide. The Al2O3-supported counterparts were also briefly studied. The catalysts were characterized by NO adsorption, TEM, XPS, W L3-edge XANES, and the magnetic measurements of Co. The Co atoms in the Co-W-S phase showed an antiferromagnetic property. The TOF of the hydrodesulfurization of thiophene on the Co-Mo(W)-S phase significantly increased as the presulfidation temperature of Mo(W)S2/SiO2 increased from 673 to 873 K, whereas it was independent of the loading of Mo(W). The TOFs on the Co-Mo-S phase and the Co-W-S phase were close to each other but strongly dependent on the support. It is suggested that complete sulfidation and the formation of stacked Mo(W)S2 particles do not necessarily result in the formation of Co-Mo(W)-S Type II.