Methods of activating catalysts for hydrodesulfurization of light gas oil (Part 1) -: Catalytic activity of CoMo/Al2O3 catalyst presulfided with polysulfides for hydrodesulfurization of dibenzothiophene

The organic sulfur compound bis-(1,1,3,3-tetramethylbutyl)-polysulfide was investigated as a novel sulfiding agent for hydrodesulfurization (HDS) catalyst by evaluating the conversion of dibenzothiophene (DBT) on a commercial Co-Mo/Al2O3 catalyst. The catalyst presulfided using the polysulfide in situ showed the same or higher activity than those using the conventional sulfiding agents dimethyldisulfide (DMDS) and CS2. The catalytic activity for HDS and hydrogenation depended remarkably on the presulfiding procedure such as type of sulfiding agent, temperature program in the presulfiding procedure, and in situ or ex situ method. The S-35 radioisotope tracer method was used to elucidate the effect of various sulfiding operation parameters on sulfur behavior on the sulfided catalyst in the HDS reaction of DBT. The effects of sulfiding agent and temperature program on the catalytic activity mainly originate from differences in the amount of labile sulfur formed in the different sulfiding processes.