Pretreatment techniques in CO-SCR and NH3-SCR: Status, challenges, and perspectives

Abstract

The selective catalytic reduction (SCR) of NO_x, utilizing carbon monoxide (CO) and ammonia (NH₃), is recognized as an effective approach for NO_x abatement. During the SCR process, the appropriate pretreatment of catalysts can significantly enhance their surface and interfacial structures, thereby improving their activity, selectivity, and stability. This review begins with the reaction mechanisms of CO-SCR and NH₃-SCR, followed by an introduction to various pretreatment strategies that can enhance the performance of catalysts employed in these two reactions. An in-depth discussion is provided regarding how different pretreatment methods influence the active structure of catalysts, the key steps of the reactions, and the overall catalytic performance. Subsequently, a comparative analysis of the pretreatment strategies employed for both reactions is presented, highlighting their similarities and differences, thereby elucidating the essence of pretreatment techniques. Lastly, the paper identifies the current challenges encountered in the field of pretreatment and proposes potential directions for future development. This work aims to offer theoretical insights that may inspire innovative pretreatment strategies in CO-SCR and NH₃-SCR among researchers and engineers.