Pore-matched activated carbon with Nanoconfined reactors for efficient NOx separation from industrial flue gas

Nitrogen oxides (NO) emitted from industrial flue gas are significant air pollutants; however, their efficient separation at room temperature remains a challenge due to the weak affinity of activated carbon (AC) for NO. In this study, we present a metal-free strategy for constructing nanoconfined reactors within commercial AC through glucose-assisted hydrothermal carbonization followed by CO 2 activation. This innovative approach facilitates dual pore regulation: glucose-derived carbon microspheres effectively narrow oversized pores, while subsequent CO 2 activation refines the structure to concentrate micropores at approximately 0.7 nm, which precisely matches the molecular dimensions of NO and creates confinement spaces conducive to catalytic oxidation. Concurrently, the process enriches stable carbonyl groups (C=O) that act as active sites within these confined spaces. The optimal material (800 AC-0.2G-180H-800C4) exhibits a micropore surface area of 432.9 m 2 /g within the 0.643–0.804 nm range and achieves a NO x adsorption capacity of 2.09 ± 0.10 mmol/g at room temperature—1.32 times higher than that of pristine AC. At 55 °C, it maintains a capacity of 0.31 ± 0.02 mmol/g, which is 3.43-fold greater than that of unmodified AC (0.07 ± 0.03 mmol/g). Kinetic analysis indicates that the confined micropores enhance the collision frequency of NO-O 2 , while carbonyl groups facilitate NO activation, together enabling efficient catalytic oxidation. Unlike metal-based modifications, this method avoids secondary pollution and allows for easy disposal of spent adsorbents. This work presents a sustainable pathway for designing high-performance carbon materials for industrial NO x abatement through the synergy of confinement and catalysis.