Hydrodesulfurization of dibenzothiophene and 4, 6-dimethyidibenzothiophene using fluorinated NiMoS/Al2O3 catalysts

A series of fluorinated NiMo/Al2O3 catalysts containing different amounts of fluorine were prepared and their activity with respect to the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was examined. The addition of fluorine modified two properties of the catalyst, namely the dispersion of metal and the acidity of the catalyst. In the HDS of DBT, the catalytic activity increased with added fluorine up to 0.5 wt.%, and then decreased with further fluorine addition due to the decrease in the surface area of the catalyst. In the HDS of 4,6-DMDBT, catalytic activity increased in proportion to the fluorine content up to 5.0 wt.%. This is possibly due to the increased surface acidity that results from the addition of fluorine.