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

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 degrees C and 4.0 MPa 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 TH-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. (C) 2014 Elsevier Inc. All rights reserved.