Local Environment and Nature of Cu Active Sites in Zeolite-Based Catalysts for the Selective Catalytic Reduction of NOx

Cu-exchanged zeolites have demonstrated widespread use as catalyst materials in the abatement of NOx, especially from mobile sources. Recent studies focusing on Cu-exchanged zeolites with the CHA structure have demonstrated them to be excellent catalysts in the ammonia-assisted selective catalytic reduction (NH3-SCR) of NOx. Thorough characterization of these materials using state-of-the-art techniques has led to a significant improvement in the understanding of active sites present, which contributes toward a fundamental understanding of the catalytic processes and the rational design of new materials; however, the availability of multiple techniques at our disposal has led to various observations and conclusions on the nature of the active sites. This article begins with a brief introduction to exhaust emission control in the mobile sector, followed by an overview of hydrocarbon-SCR and NH3-SCR; the former technology having found common use in light duty passenger vehicles, whereas the latter are applie...

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