EFFECT OF SULFIDING PRESSURE ON THE FORMATION OF THE NI SITE ON NI-MOAL2O3 AND NI-W/AL2O3/

The effect of sulfiding pressure on the surface structure of Ni-Mo (or W)/Al2O3 was investigated in the range of 0.1 to 5.1 MPa by in-situ F T-IR/DRA of adsorbed NO. The distribution of the Ni site and Mo (or W) site on the surface of every catalyst examined was sensitive to the s ulfiding pressure, In the Ni-Mo/Al2O3 catalyst, the intensity of the M o site-band was weaker when the catalyst was sulfided at a pressure ab ove 1.1 MPa than when sulfided at 0.1 MPa, while the Ni site-band was insensitive to the sulfiding pressure. On the other hand, in the Ni-W/ Al2O3 catalyst, the W site-band could not be discriminated distinctly in the range of 0.1 to 5.1 MPa and the Ni site-band sensitively decrea sed with increasing the sulfiding pressure, Comparing the results with those of the physical mixture of Mo(or W)/Al2O3 and Ni/Al2O3, it was suggested that sulfiding induces the interaction between Ni and Mo in Ni-Mo/Al2O3 (or W in Ni-W/Al2O3), and that the interaction between Ni and Mo was promoted by higher pressure sulfiding above 1.1 MPa. (C) 19 97 Elsevier Science B.V.