Chitosan derived nitrogen-doped microporous carbons for high performance CO₂ capture

Nitrogen-doped microporous carbons were fabricated by a simple chemical activation strategy in which chitosan and K₂CO₃ were employed as the precursor and activation agent, respectively. The textural and chemical properties of the porous carbons could be easily tuned by changing the ratio of K₂CO₃/chitosan and activation temperature. Due to their large pore volume, well-defined microporosity and relatively high nitrogen content, these porous carbons were applied as adsorbents for CO ₂ capture and demonstrated excellent CO₂ uptake performances. In particular, the sample prepared at 635 C with K ₂CO₃/chitosan ratio = 2 shows a CO₂ uptake as high as 3.86 mmol g^-1 at 25 C, 1 atm. Furthermore, the CO₂ uptake remains almost constant in five consecutive adsorption-desorption cycles, indicating this material has great stability and recyclability as a CO₂ sorbent. In addition, an extraordinary separation selectivity against N₂ (CO₂/N₂ selectivity of ca. 21) was also observed.