PHASE-COMPOSITION OF ALUMINUM-NICKEL-MOLYBDENUM OXIDE CATALYSTS FOR HYDROTREATMENT - THE NATURE OF THE ACTIVE PHASE

The phase composition of aluminum-nickel-molybdenum oxide catalysts (A NMC) with various MoO3 and NiO contents is studied by XRD, diffuse-ref lectance electron spectroscopy, O-2 chemisorption on the reduced sampl es, and selective extraction of Mo and Ni compounds. The results of th e phase analysis are compared to the data on catalyst tests in thiophe ne hydrogenolysis. The phase composition of ANMC is shown to involve t he surface analog of a heteropolymolybdenum compound (HPC). The conten t of the latter, which was found by extraction with water, correlates well with the O-2 chemisorption data and partially with the catalytic activity. Finally, HPC is determined to be the oxide precursor of the active sulfide phase.