Effects of H_2S on HDS Reaction of Dibenzothiophene and 4,6-Dimethyl-dibenzothiophene over NiW/Al_2O_3 and CoMo/Al_2O_3 Catalysts

The effects of H_2S on the catalytic activity of sulfided NiW/Al_2O_3 and CoMo/Al_2O_3 for hydrodesulfurization (HDS) reaction of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) were investigated. The addition of H_2S inhibited the HDS reactivity of DBT and DMDBT, but the effect on the HDS action of DBT was more obvious. In the HDS reaction of DBT and DMDBT over NiW/Al_2O_3, H_2S inhibited the direct desulfurization and the hydrogenation routes. Similar inhibition occurred in the HDS reaction of DBT over CoMo/Al_2O_3, however, in the case of DMDBT, H_2S suppressed direct desulfurization route while promoted hydrogenation route. NiW/Al_2O_3 was more susceptible to H_2S than CoMo/Al_2O_3.