Alkali metal promotion of NO_x decomposition over cobalt oxide

NO decomposition is the most attractive method of NO_x abatement. This reaction is favored thermodynamically, but does not proceed with appreciable rate over most catalysts studied. The most active NO decomposition catalyst to-date is the Cu-ZSM-5 catalyst. Of the simple metal oxides, Shelef has determined that Co₃O₄ is the most active catalyst. Its rate of reaction is still orders of magnitude lower than that of Cu-ZSM-5. Hamada et al. found that addition of Ag to Co₃O₄ greatly enhances the activity of Co₃O₄. It is not clear whether different reaction mechanisms are operative for different catalysts, however the inhibitory effect of oxygen is common to all catalysts.