Different role of H2S and dibenzothiophene in the incorporation of sulfur in the surface of bulk MoP during hydrodesulfurization

The surface of MoP becomes sulfided during hydrodesulfurization (HDS) of dibenzothiophene (DBT), and the HDS activity increases with time on stream, showing that the sulfided MoP surface is more active than the fresh MoP surface. MoP pretreated with H2S/H2 under HDS reaction conditions showed the same activity increase as fresh MoP, but XPS did not show any sulfur at the surface of the pretreated MoP. Hence, the sulfur that is incorporated into the MoP surface during the HDS of DBT originates from DBT rather than from H2S.