High-pressure DTA (differential thermal analysis) studies on HDS (hydrodesulfurization) catalysts

High-pressure DTA (Differential Thermal Analysis) studies on HDS (hydrodesulfurization) catalysts were carried out by heating seven commercial petroleum HDS containing 12-18 3< molybdenum oxide and smaller amounts of other oxides and organic sulfiding reagents in a hydrogen stream to 450/sup 0/C at a rate 5/sup 0/C/min. The reactivity of tert.-butyl sulfide, tert.-butyl disulfide, carbon disulfide, C/sub 4/-C/sub 5/ n-alkyl disulfides, allyl sulfide, thiophene, and C/sub 2/-C/sub 4/ n-alkyl sulfides decreased in the order given; the reactivity of benzothiophene was equal to that of the n-alkyl sulfides. The reactivity of the catalyst was related mainly to the promotor metal (cobalt, nickel, and/or silicon) present, rather than to the catalyst preparation procedure. A reaction mechanism by which the sulfiding reaction of HDS catalysts with allyl sulfide, tert.-butyl sulfide, and tert.-butyl disulfide proceeds via decomposition to produce hydrogen sulfide, which reacts with the catalyst, is proposed.