Interaction between Mo and Co on Co-Mo/Al2O3 sulfided at high pressure (≤5.1 MPa) by means of high pressure DRIFT and EXAFS method

Co-Mo/Al(2)O(3) was sulfided at high pressure (less than or equal to 5.1 MPa) and was supplied for in-situ DRIFT measurement using NO as a surface probe molecule. The IR band of NO adsorbed on Co site was much stronger than that of Mo site, and the IR intensity ratio of Co site band to Mo site band was much higher when Co-Mo/Al(2)O(3) was sulfided at the pressure above 1.1 MPa than when it was sulfided at atmospheric pressure. Mo/Al(2)O(3), Co/Al(2)O(3) and the physical mixture of them were also supplied for the high pressure DRIFT measurement. In the DRIFT spectra of the physical mixture, the intensity of the Mo site band was comparable to that of the Co site band. In the spectra of Ni-Mo/Al(2)O(3), only the Ni site band was observed. Mo K-edge EXAFS showed that the dispersion of Mo of Co-Mo/Al(2)O(3) is almost the same as that of the physical mixture and does not depend on the sulfiding pressure. Combining the results of the DRIFT spectra with that of Mo K-edge EXAFS, it was suggested that Co-Mo interaction induces selective formation of CUS on Co site on Co-Mo/Al(2)O(3) and the interaction is promoted by higher pressure sulfiding. (C) 1997 Elsevier Science B.V.