Research progress of Cu-based catalysts for selective catalytic reduction of NO<italic>_x</italic> with CO

Nitrogen oxides (NOx) are an important factor that causes ecological environmental problems and affects human health, representing simultaneously one of the most recalcitrant air pollutants to eliminate. The conventional ammonia selective catalytic reduction (NH3-SCR) confronts many challenges, such as ammonia slip and irreversible poisoning deactivation of the catalysts. Consequently, research emphasis has shifted toward the carbon monoxide selective catalytic reduction (CO-SCR), in which CO serves as the reductant. CO-SCR is currently regarded as a promising denitration technology that enables the simultaneous abatement of CO and NOx, thereby fulfilling the concept of “treating waste with waste”. It also eliminates the need for additional reducing agents, avoiding the risk of secondary pollution, and thus exhibits irreplaceable advantages in flue gas treatment. An efficient catalyst is the core of the CO-SCR, compared with noble metal catalysts, transition metal Cu-based catalysts have been extensively studied due to their low cost, variable valence states and excellent catalytic performance. This paper reviews the applications of a variety of supported mono-metallic catalysts, supported bimetallic Cu-based catalysts, and non-supported bimetallic Cu-based catalysts in the CO-SCR process. Introduces the catalytic performance of the catalysts, as well as the influences of carrier types and morphologies, different metal components and their interactions. Meanwhile, it also provides an overview of the reaction mechanisms about Cu-based catalysts in the CO-SCR process. This study provides theoretical basis and research directions for the development and application of novel catalysts in the future.