A SEM-EDS study of new and used automotive catalysts Original Research Article

Automotive catalyst deactivation by inorganic contaminants orginating in engine oil and fuel is discussed. Scanning electron microscopy images and energy dispersive spectroscopy analysis were used to characterize the variation of contaminant relative concentrations in various types of used monolithic catalysts. The major contaminants were calcium, phosphorus, sulphur, lead, iron and zinc. All contaminants seems to have a cumulative time dependent effect, acting more as foulants than as poisons. Valuable information about the washcoat composition were derived. A preliminary acetic acid leaching test showed that a significant quantity of the contaminants may be easily removed from the catalyst surface.