The further activation and functionalization of semicoke for CO₂ capture from flue gases

To systematically study CO₂ adsorption performance, semicoke from the low-rank lignite was further activated and functionalized for CO₂ capture from flue gases. The effect of the activation conditions, such as the activation temperature, activation time and HCl washing, and the tetraethylenepentamine (TEPA)-functionalization on CO₂ adsorption were investigated; the pore structure and surface morphology of the semicoke under different activation conditions were characterized. Both the surface structure and adsorption performance of the activated semicoke could be improved under appropriate activation and acid-treatment conditions. The optimal breakthrough and equilibrium adsorption capacity for the TEPA-functionalized HCl-washed activated semicoke were separately 2.68 and 3.70 mmol g^-1 at 60 °C for the simulated flue gas of 15 vol% CO₂ and 85 vol% N₂. After ten adsorption-desorption cycles, the equilibrium adsorption capacity was still 3.43 mmol g^-1, and the semicoke-based sorbent showed good regenerability.