The State of the Art in Selective Catalytic Reduction of NO x by Ammonia Using Metal‐Exchanged Zeolite Catalysts

An overview is given of the selective catalytic reduction of NO<sub>x</sub> by ammonia (NH<sub>3</sub>‐SCR) over metal‐exchanged zeolites. The review gives a comprehensive overview of NH<sub>3</sub>‐SCR chemistry, including undesired side‐reactions and aspects of the reaction mechanism over zeolites and the active sites involved. The review attempts to correlate catalyst activity and stability with the preparation method, the exchange metal, the exchange degree, and the zeolite topology. A comparison of Fe‐ZSM‐5 catalysts prepared by different methods and research groups shows that the preparation method is not a decisive factor in determining catalytic activity. It seems…