Highly active unsupported NiMo sulfide catalysts from direct hydrothermal synthesis for deep hydrodesulfurization of 4,6-dimethyldibenzothiophene

Unsupported NiMo sulfide catalysts were prepared using ammonium tetrathiomolybdate (ATTM) and nickel nitrate by a hydrothermal synthesis method. The HDS activity of these catalysts was much higher in the simultaneous HDS of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) than that of the commercially available NiMo/Al₂O₃ sulfide catalysts under high H₂ pressure, temperature, and in the presence of organic solvent. The unsupported NiMo sulfide catalysts showed higher activity for hydrogenation (HYD) pathway than the direct desulfurization pathway in HDS of DBT, which was in distinct contrast to the commercial HDS catalysts. The same trends were observed for HDS of 4,6-DMDBT where the unsupported NiMo sulfide catalysts promoted the desulfurization mainly through HYD pathway. The hydrothermal preparation conditions may help ATTM to be decomposed and react with Ni precursor and finally form small (nano) size of NiMo sulfide cluster. This is an abstract of a paper presented at the 231st ACS National Meeting (Atlanta, GA 3/26-30/2006).