Synthesis of Porous Carbons with High N-Content from Shrimp Shells for Efficient CO₂-Capture and Gas Separation

High N-content porous carbons are successfully synthesized from shrimp-shells as an appropriate solid adsorbent for CO₂ capture and CO₂/N₂ (fuel gas), CO₂/CH₄ (biogas), and CH₄/N₂ (coalbed gas) binary mixture separation. The resultant porous carbons exhibited a well-developed pore texture (specific surface area up to 1984.7 m² g^-1, pore volume up to 1.00 cm³ g^-1) and a high N-content up to 5.06 wt %. These favorable properties of carbon led to excellent CO₂ adsorption capacities of 6.82 and 4.20 mmol g^-1 at 1 bar, 273 and 298 K, respectively. The different pore sizes govern the CO₂ adsorption at low/high temperatures. Furthermore, superior separation selectivities for binary gas mixture pairs (CO₂/N₂= 47, CO₂/CH₄= 8, and CH₄/N₂= 5, at 298 K and 1 bar) were predicted by the IAST model. The N functionality and pore volume affect the gas-mixture selectivity. The outstanding adsorption and separation performances coupled with effective transient breakthrough behavior make these porous carbons potent adsorbents for commercial applications. This work has developed a promising solution for converting biowastes into a high-value product for environmental and energy applications.