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.