$NO_x$ storage/reduction catalysts based on Mg/Zn/Al/Fe hydrotalcite-like materials

Mg/Zn/Al/Fe mixed oxides derived from hydrotalcites synthesized by the coprecipitation method were found to be effective catalysts for the NO x storage/reduction (NSR) process. The activity of this material was improved by the addition of a basic metal as potassium and by the incorporation of a metal with sig- nificant redox properties as Pd. It seems that palladium favored the NO oxidation to NO 2 whilst potas- sium increased the surface basicity of the catalyst, both improving the NO x storage. This catalyst was hydrothermally stable and showed a similar activity to that obtained with a catalyst derived from Mg/ Co/Al hydrotalcites but without the environmental problems related with the use of cobalt