STUDIES OF MOLYBDENUM SULFIDE CATALYST EX AMMONIUM TETRATHIOMOLYBDATE- EFFECT OF PRETREATMENT ON HYDRODESULFURIZATION OF DIBENZOTHIOPHENE

Alumina-supported molybdenum sulfide catalyst was prepared by the deco mposition of ammonium tetrathiomolybdate (ATTM) and tested in the hydr odesulfurization (HDS) of dibenzothiophene (DBT). The HDS activity of unpromoted and Co-promoted molybdenum sulfide catalysts was found to d epend strongly on the activation procedure of the catalyst. In all cas es, the activity of the Go-promoted catalyst was superior to that of t he ATTM counterpart. Surface characterization of the catalyst subjecte d to different pretreatments was carried out by X-ray photoelectron sp ectroscopy and FTIR spectroscopy of NO probe. The pretreatments were e ffective in obtaining a highly dispersed heterometallic sulfide phase and a good synergy between Co and molybdenum sulfide. (C) 1998 Elsevie r Science B.V.