Challenges and insights in CO adsorption using N-doped carbons under realistic conditions.

N-doped carbon was synthesized from an N-rich precursor, chitosan, and systematically compared with materials reported in the literature to evaluate its potential for CO capture in post-combustion scenarios and biogas upgrading under realistic conditions. The synthesized material, with 5.2 at.% nitrogen and a high surface area of 1000 m g, exhibited moderate CO uptake (2.6 mmol g) and an ideal CO/N selectivity (S) of 20.4 under post-combustion conditions (15% vol. CO, 1 bar, 298 K). For equimolar CO/CH mixtures (50% vol. CO), the material showed an ideal CO/CH selectivity (S) of 3.3 under the same conditions. When exposed to humidity, the material adsorbed CO efficiently at low relative humidity (RH) levels, but suffered a significant loss of capacity at 30% RH, attributed to water-induced site blocking. A comparison with other N-doped/enriched materials from the literature revealed difficulties in correlating CO adsorption and selectivity with specific material properties, such as surface area and nitrogen content. This underscores the complexity of defining universal design principles for CO capture.