Effect of boron addition on the surface structure of Co-Mo/Al2O3 catalysts

The effect of boron addition was studied on the surface structure of Co-MoS2/Al2O3 catalysts prepared by an impregnation technique. A chemical vapor deposition (CVD) technique using Co(CO)3NO was applied to evaluate the maximum potential hydrodesulfurization (HDS) activity of the catalysts, the extent of blocking of MoS2 edges by cobalt sulfides, and the coverage of Co on the MoS2 edges. The catalysts were characterized by means of UV–vis spectroscopy and magnetic susceptibility measurements. The addition of boron decreased the catalytic activity of Co-MoS2/Al2O3 for the HDS of thiophene, irrespective of calcination and Co loading. However, the extent of increased HDS activity of Co-MoS2/Al2O3 from the addition of Co using the CVD technique was greater for the boron-containing catalysts than for the corresponding boron-free catalysts. Characterization by the CVD technique showed that boron significantly increased the extent of blocking and decreased the Co coverage on MoS2 edges. The surface structure of uncalcined Co-MoS2/Al2O3 catalysts estimated by use of the CVD technique was substantiated by the magnetic property of Co.