Study of Co(or Ni)-Mo Oxide Phase Transformation and Hydrodesulfurization Catalysts by Raman Microprobe Equipped with New Cells

Heating cells used in optical microscopy are adapted to a laser Raman microprobe to an under air study of the solid phase transformation of cobalt and nickel molybdates in which the molybdenum atoms are in tetrahedral oxygen environment ([a] phase) or in octahedral environment ([b] phase). In each case, the Co or Ni environment is octahedral. In the second part of this paper, a newly designed controlled-atmosphere and temperature cell is described. It permits the study of several problems particularly those related to the reactivity of Co or Ni-Mo-γ-Al2O3 hydrodesulfurization catalysts. Results on (1) sulfidation of the oxide precursor form catalysts by a H2-H2S mixture, (2) interaction with a model sulfided molecule: thiophene, and (3) pyridine chemisorption are reported.