Kinetic Study of 4,6-Dimethyldibenzothiophene Hydrodesulfurization over Ni Phosphide, NiMo and CoMo Sulfide Catalysts

HDS of 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS over a Ni₂P/USY phosphide catalyst and two commercial sulfide catalysts was conducted and the rate constants of the three catalysts for the two pathways were measured. The method based on the initial selectivity was the most reasonable for estimating k₁ (pseudo first-order rate constant for the hydrogenation pathway) and k₂ (pseudo first-order rate constant for the hydrogenolysis pathway) values among the methods examined. NiMo catalyst was better than CoMo for deep HDS of 4,6-DMDBT because of its higher hydrogenation activity. However, if ranked based on active sites, then the catalytic activity would appear to be Ni phosphide > NiMo sulfide > CoMo sulfide. Transition metal phosphide could have good activity for HDS of 4,6-DMDBT and might become promising catalyst for deep HDS with some further.