Characteristics of an Advanced Carbon Sorbent for CO2 Capture

Abstract

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.