Vanadium-based sulfides as hydrotreating catalysts

The V deposit obtained in petroleum feedstocks hydrodemetallation can leads to significant change for the hydrotreating catalyst activity. Actually, although vanadium sulfide solids have shown only moderate activities, these are significant and higher than predicted by the more accepted theoretical models. A complete review of the activity of these sulfides, bulk or supported, pure or in presence of a promoter is proposed. A mechanism based on a charge transfer leading to change in the energy levels of the electronic bands is proposed as tentative explanation for the synergetic effect observed for the binary vanadium-transition metal sulfides.