Nitrogen/Oxygen Co-Doped Porous Carbon Derived from Biomass for Low-Pressure CO<sub>2</sub> Capture
Dawei Wu, Jing Liu, Yingju Yang, Ying Zheng
Abstract
Nitrogen/oxygen co-doped porous carbon with excellent textural properties was synthesized from biomass for CO2 capture using the freeze-drying and nonthermal plasma treatment methods. Quantum chemical calculations were performed to reveal the CO2 adsorption mechanism. Various nitrogen and oxygen functional groups can be produced on the carbon surface during air plasma treatment. Plasma treatment hardly influences the morphology and textural properties of porous carbon. The plasma-modified sample PC-A10 exhibits the highest CO2 adsorption ability of 37.90 mg/g in the simulated flue gas at 30 °C. The superior capture performance is closely associated with the existence of nitrogen and oxygen functional groups produced from plasma treatment. The porous carbon shows excellent regeneration ability. CO2 adsorption capacity does not significantly degrade over five adsorption/desorption cycles. Kinetic analysis indicates that CO2 adsorption in porous carbon takes place at high rates. The pseudo-second-order and the Bangham adsorption models can describe well the CO2 adsorption kinetics. The results of DFT calculations indicate the physical sorption nature of CO2 adsorption by porous carbon. Pyridine-typed carbon surface has the highest attraction for CO2 molecules. No significant electrons are transferred between the CO2 molecule and the carbon surface.