CO2/NOx storage and reduction (CNSR) technology—a new concept for flue gas treatment†

The emission of CO₂ and NO_x from industrial factories poses significant challenges to human health and contributes to extreme climate change. NO_x storage and reduction (NSR) and integrated CO₂ capture and methanation (ICCM) technology are some of the effective technologies used to deal with NO_x and CO₂, respectively. However, there is currently no relevant technology available for the simultaneous removal of both NO_x and CO₂ gases co-existing in flue gas. This paper proposes a new concept named CO₂/NO_x storage and reduction (CNSR) for the first time. This approach utilizes a K–Pt/Ni₃Al₁O_x dual functional material (DFM) to achieve co-storage of CO₂ and NO_x, followed by their reduction to CH₄ and N₂, respectively. The CNSR tests demonstrate the feasibility of this technology. At 350 °C, the conversion for CO₂ and NO_x was 60.8% and 99.5%, with CH₄ and N₂ selectivity of 98.9% and 90.3%, respectively. After 10 cycles, the sample exhibited a relatively stable CO₂ conversion of around 66%, with CH₄ selectivity remaining above 90%. The conversion of NO_x remained essentially unchanged at close to 100%. Furthermore, a possible mechanism for the CNSR process is proposed in this study. We believe that this work will provide a novel strategy for the treatment of multi-component gaseous pollutants in flue gas.