Hydrodesulfurization of 4,6-dimethyldibenzothiophene and its hydrogenated intermediates over bulk Ni2P

[Display omitted] •Kinetics of the HDS of 4,6-dimethyldibenzothiophene over Ni2P.•A fast dehydrogenation of tetrahydro-4,6-dimethyldibenzothiophene (TH-4,6-DMDBT).•Methyl group migration during the dehydrogenation of TH-4,6-DMDBT.•Inhibition of desulfurization by piperidine depends on reactant. The hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT) and its hydrogenated intermediates 1,2,3,4-tetrahydro-4,6-dimethyldibenzothiophene (TH-4,6-DMDBT) and 1,2,3,4,4a,9b-hexahydro-4,6-dimethyldibenzothiophene (HH-4,6-DMDBT) over a bulk Ni2P catalyst was studied at 340°C and 4.0MPa in the presence and absence of piperidine. The rate constants of all steps in the network of the HDS of 4,6-DMDBT were measured. The HDS of 4,6-DMDBT occurred predominantly through the hydrogenation (HYD) pathway, and the HYD and direct desulfurization pathways were about equally inhibited by piperidine. Piperidine inhibited the desulfurization of TH-4,6-DMDBT and 4,6-DMDBT in the same way, but did not affect that of HH-4,6-DMDBT. In contrast to the HDS of TH-4,6-DMDBT over metal sulfide catalysts and to the HDS of TH-DBT, a fast dehydrogenation of TH-4,6-DMDBT to 4,6-DMDBT was observed. Besides 4,6-DMDBT, a small amount of the methyl-migration isomers was detected in the dehydrogenation product of TH-4,6-DMDBT, which is ascribed to the metallic character of Ni2P.