Highly selective CO2 capture by nitrogen enriched porous carbons

A series of nitrogen enriched microporous carbons were facilely prepared by KOH activation using melamine-doped phenolic resins as precursors. The activated carbons show high CO2 uptakes up to ca. 1.3 mmol g−1 under low pressure (0.15 bar, 25 °C), which can be ascribed to not only their optimal fraction of ultramicropores but also the high N-contents. One of the samples even exhibits excellent adsorption selectivity for CO2 over N2 (i.e., selectivity factors of 43.7 and 52.9 obtained from initial slope and IAST calculations, respectively). Furthermore, the preferential CO2 uptake of the carbons was confirmed by successive breakthrough experiments under post combustion flue gas stream conditions (15% CO2 concentration, 1 bar and 25 °C). Since these carbons also feature good stability over repeated thermal cycling and ease of regeneration, their practical applications in post combustion CO2 capture shall lie within the realm of possibility.