MD//MO and MD//W [MD = Mn, Fe, Co, Ni, Cu and Zn] promotion via spillover hydrogen in hydrodesulfurization

The promotion effect of Mn, Fe, Co, Ni, Cu and Zn sulfides on the hydrodesulfurization (HDS) activity of Mo and W sulfides, under experimental conditions like industrial ones, using staked beds, was studied. Synergism between staked beds in all the studied pairs, with a magnitude that leads a volcano curve with a maximum in Co and Ni sulfides was detected. Promotion was well explained by the formation of spillover hydrogen (Hso) in the first bed (in which Mn, Fe, Co, Ni, Cu or Zn sulfides supported on gamma-Al2O3 were located) that migrate to the second bed (in which Mo or W sulfides supported on gamma-Al2O3 were located), 5 mm below.