Highly Efficient Bimetallic Catalysts Supported on Carbon Nanotubes for the NOx Reduction

Nitrogen oxides represent a major source of concern related to atmospheric pollution, causing substantial impacts on human health. One innovative approach to reducing these emissions, and a promising alternative to conventional methods using NH₃, is selective catalytic reduction with carbon (SCR-C). The aim of this study is the development of carbon-based catalysts that are active in the reduction of NO. For that, carbon nanotubes were subjected to treatments to modify their surface chemistry, including introducing oxygen and nitrogen groups, as well as potassium (K) and copper (Cu) incorporated as metal phases. In their original form, carbon nanotubes do not exhibit catalytic activity in reducing NO. However, catalytic performance is significantly improved by the addition of surface groups and Cu. Adding K to the support notably contributes to increasing the catalytic performance. N-doped carbon nanotubes impregnated with copper and potassium (CNT_M_BM@5Cu5K) achieved complete NO reduction at 360 °C. In this catalytic system, the formation of CO₂ and N₂ was observed and CO was not identified. Furthermore, although N₂O was detected during the reaction, its amount was very low compared to the N₂ and CO₂ products. The stability of this catalyst was investigated over 87 h continuous test, revealing deactivation after 41 h of reaction.