CHARACTERIZATION OF SUPPORTED MOLYBDENUM SULFIDE CATALYST EX AMMONIUMTETRATHIOMOLYBDATE

Active sulfide catalysts are conventionally prepared by converting the respective oxides to sulfides. Reductive sulfiding of the oxides is u sually difficult and does not proceed in a regular manner. A supported molybdenum sulfide catalyst prepared by the decomposition of ammonium tetrathiomolybdate (ATTM) in hydrogen is unique in two respects, name ly, the lower valence state of the supported molybdenum sulfide cataly st, and the presence of few oxygen atoms in the catalyst. The activity of a catalyst prepared by this technique (and subjected to different pretreatments) is compared with the activities of both a conventional and a commercial catalyst. The pretreatment consists of flash or tempe rature-programmed decomposition of the supported ATTM in helium follow ed by removal of excess sulfur by temperature-programmed reduction, or the decomposition of supported ATTM in hydrogen. The results clearly indicate that the activity of the catalyst prepared by the decompositi on of ATTM is higher than the activities of both the conventionally pr epared catalyst and the commercial catalyst.