STUDY OF CO(OR NI)-MO OXIDE PHASE-TRANSFORMATION AND HYDRODESULFURIZATION CATALYSTS BY RAMAN MICRO-PROBE 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 molybates in which the molybdenum atoms are in tetrahedral oxygen environment ( left bracket a right bracket phase) or in octahedral environment ( left bracket b right bracket phase). In each case, the Co or Ni environment is octahedral. 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- gamma -Al//2O//3 hydrodesulfurization catalysts. Results on (1) sulfidation of the oxide precursor form catalysts by a H//2-H//2S mixture, (2) interaction with a model sulfided molecule; thiophene, and (3) pyridine chemisorption are reported.