New Hypothesis Explaining Synergy Between 2 Phases in Heterogeneous Catalysis - Case of Hydrodesulfurization Catalysts

We propose a new mechanistic model, explaining the properties of catalysts composed of sulfides of Group VI and sulfides of Group VIII metals. Spill-over hydrogen, emitted by the latter, modulates, or controls, the catalytic centers at the surface of the former sulfide. Slightly reduced centers formed by spill-over hydrogen would be active in hydrogenation, and deeply reduced centers, in hydrodesulfurization. The theory resting on this concept of a remote control agrees qualitatively with all the known catalytic and physico-chemical properties of the catalysts.