Characteristics of an advanced carbon sorbent for CO2 capture

The adsorption and desorption characteristics on an advanced carbon sorbent for gases present in the flue gas stream, including CO2, N2, O2, Ar, H2O vapor, and impurities NO and SO2 are discussed. At 5 °C and 1 atm CO2 pressure, this carbon sorbent can uptake 20 wt% (or 4.5 mmol/g) of CO2, with high Henry’s law selectivity over N2, O2, and Ar. The heat of adsorption for CO2 decreases from ∼28 kJ/mol (290 meV) to ∼25.7 kJ/mol (260 meV) as the coverage of CO2 increases; whereas the heat of adsorption for N2, O2, and Ar is in the range of 16–17 kJ/mol. The carbon sorbent has a high surface area of 1270 m2/g, high thermal conductivity (0.8 W/m K), low heat capacity (1 J/g K), high mechanical strength, and high attrition resistance. It is an ideal candidate for post-combustion CO2 capture using rapid pressure swing and rapid temperature swing methods.