Catalysts Examined by Electron Spin Resonance-Examples from Hydrodesulfurization Catalysis

Abstract

The utility of electron spin resonance (ESR) for catalyst characterization is illustrated for the desulfurization catalysts used to remove sulfur, nitrogen, and organically bound metals from petroleum. These catalysts consist of active metals (Mo, W, Co, Ni) in mixed oxide and sulfide phases on high surface area alumina supports. Coordinated studies of unsupported sulfide and oxide model systems determine the chemical form and number of defect sites on the actual catalysts. Parallel catalysis studies correlate ESR defects and catalytic activity for many reactions.