(345b) CO2 capture in Nitrogen-Doped Porous Carbons Synthesized from Biomass

In this work, nitrogen-dope and highly porous carbons were synthesized from lignin biomass along with successive activation with potassium hydroxide and ammonia. The resultant carbons had a BET surface area of 1631-2922 m²/g and nitrogen content 5.6-7.1 at.%. Different nitrogen functionalities include pyridinic, amino, pyrrolic/pyridonic, nitro and nitroso groups. High surface area and nitrogen functionalities resulted in high carbon dioxide adsorption capacity of 5.48 and 8.6 mmol/g in 298 K and 273 K, respectively, and pressure upto 1 bar. The selectivity for CO₂/N₂ was calculated using the Ideal Adsorbed Solution Theory (IAST). The results indicated that selectivity increases with the increase in nitrogen content. IAST calculations were also employed to calculate the binary adsorption isotherms to simulate mixed gas adsorption for CO₂ and N₂ as a function of total pressure and mole fraction of CO₂ in the feed gas mixture. A stability study with 10 continuous cycles of adsorption and desorption indicated no loss of adsorption capacity. A breakthrough experiment with (10/90) CO₂/N₂ mixture in a dynamic column experiment confirmed the physical separation of the two components. The overall results suggest that these carbons can be used as potential adsorbents for CO₂ capture purposes.