CO₂ adsorption at nitrogen-doped carbons prepared by K₂CO₃ activation of urea-modified coconut shell

This article reports on the synthesis and characterization of porous nitrogen-doped carbons synthesized by carbonization of coconut shell followed by urea modification and K₂CO₃ activation. The as-synthesized samples were carefully characterized by various techniques. This series of samples demonstrate high CO₂ uptake at 1bar, up to 3.71mmol/g at 25°C in addition to 5.12mmol/g at 0°C. Furthermore, these sorbents possess fast CO₂ adsorption kinetics, stable reusability, moderate heat of CO₂ adsorption, reasonable CO₂/N₂ selectivity, and high dynamic CO₂ capture capacity under simulated flue gas conditions. It is found that, in addition to nitrogen content and narrow micropore volume, the pore size distribution of narrow micropore also plays a major role in determining the CO₂ capture capacity under ambient condition. This work is intended to provide useful information and to inspire ways to develop new carbonaceous sorbents for removing CO₂ from combustion flue gas.