Abstract:The reduction of nitrogen oxides (NO) in industrial flue gas is crucial for achievingcoordinated control of fine particulate matter (PM) and ozone (O) in China′s atmosphere. The mostcommon NO removal method for stationary sources is selective catalytic reduction (SCR) technologyusing NH as a reducing agent, referred to as NH-SCR. However, the negative effects associated withNH introduction, such as secondary pollution caused by NH slip and higher carbon emissions, havegradually attracted widespread attention in recent years. This article provides a review and outlook onthe research status and application prospects of selective catalytic reduction technology using carbonmonoxide (CO) as a reducing agent (CO-SCR). Research has shown that developing high-performancecatalysts is the key challenge for CO-SCR technology. CO-SCR catalysts can be broadly categorizedinto two types: transition metal oxides and supported noble metal materials. Typical catalysts, includingEnergy Environmental ProtectionCu-, Co-, Mn-, and Ir-based catalysts, are reviewed in this article. The microscopic reaction process ofCO-SCR involves three main steps: (1) the adsorption of reactant molecules, (2) the conversion ofintermediate molecules, and (3) desorption and diffusion of product molecules. Among these steps, thepreferential adsorption of NO molecules on the active site, followed by dissociation, is the rate-determining step. The interaction between NO and the substrate strongly depends on the surface stateand tends to occur at oxygen vacancies on transition metal oxides, while it occurs at unsaturatedcoordination cation centers on supported noble metal materials. In addition, the impact of CO/NO,oxygen (O), sulfur dioxide (SO), and water vapor (HO) on CO-SCR performance has also beendiscussed in detail. For example, on the surface of Ir-based catalysts, Ir (serving as the main active site)is unlikely to remain unchanged throughout the entire reaction process. It is anticipated that Ir will beconverted to oxidized Ir after donating electrons to the antibonding π* orbital of the NO molecule. Ifnew electrons are not replenished promptly, the catalytic activity will gradually decrease as oxidized Irbecomes the predominant species, which is the primary reason for the poor stability of the catalyst in thepresence of O. Interestingly, SO stabilizes the catalyst and facilitates the generation of Ir sites underO-containing conditions. Therefore, future research should prioritize the development of catalyststailored to specific applications, and refine the CO-SCR reaction model under diverse conditions, with afocus on synergistic technologies such as the selective circulation coupling of CO-SCR in steel sinteringflue gas. Furthermore, the high cost of catalysts remains a crucial obstacle hindering the widespreadadoption of CO-SCR technology. Close-