A Comparison of Some Catalytic Properties of Unsupported MOS2 and WS2 Catalysts Promoted by Group VIII Metals

Abstract

AbstractUnsupported sulfided CoMo, NiMo, CoW and NiW catalysts prepared by comaceration (CM) method and homogeneous sulfide precipitation (HSP) method have been studied in hydrodesulfurization of dibenzothiophene and hydrogenation of biphenyl.Comparison of intrinsic rates shows that, for both reactions, the HSP catalysts are more efficient than the corresponding CM samples. Moreover, the promoting effect of Ni in hydrogenation is substantially higher than that of Co.From decomposition of the precursors, followed by differential thermal analysis, a parallelism appeared between all mixed catalysts prepared by the same procedure. For CM precursors, the decomposition features show the persistence of the character of Mo and W compounds and confirm the limited interaction existing between Co (or Ni) and Mo (or W) in the precursor state. On the contrary, for HSP precursors the exothermic peak is always recorded at a much lower temperature and a comparison with previous results obtained on CoMo (CM) and CoMo (HSP) catalysts suggests that a mixed phase probably exists in all the HSP samples.