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

• Mg/Zn/Al/Fe hydrotalcite-like materials are active catalysts for the NSR process.
• Zn and Fe in the structure of the Mg/Al hydrotalcite improves the redox properties of the material.
• NO adsorption is maximized by the introduction of basic specie in the hydrotalcite.
• The material is hydrothermally stable and no deactivation appears after aging.

Mg/Zn/Al/Fe mixed oxides derived from hydrotalcites synthesized by the coprecipitation method were found to be effective catalysts for the NOx 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 significant redox properties as Pd. It seems that palladium favored the NO oxidation to NO2 whilst potassium increased the surface basicity of the catalyst, both improving the NOx 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.

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