An economic one-step solvent-free method to synthesize N, S co-doped porous carbons for efficient CO2 capture

Biomass porous carbon has a bright prospect in realizing efficient carbon capture because of its low price and simple synthesis. In this study, N, S co-doped porous carbon was prepared easily and conveniently by using waste coconut shell as raw material, potassium hydroxide as activator and thiourea as dopant through a one-step solvent-free method, which requires low-energy consumption. Potassium hydroxide was chosen as activator leading to abundant aperture (V-t = 0.94 cm3/g) and specific surface area (S-BET = 1392.74 m2/g) of the porous carbon. The characterization results demonstrate that the sample CS-112-600 contains both N (6.36%) and S (3.65%) atoms, which could facilitate the interaction between CO2 molecules and porous carbon. The optimal sample exhibits the highest capacity of 2.32 mmol/g at 25degree celsius and 4.08 mmol/g at 0degree celsius under 1 bar. Besides, the adsorption kinetics and isotherms on CS-112-600 were perfectly described by PFO model and RP model, respectively, indicating that the adsorption was a rapid process and dominated by physical effect. The fabricated sorbent demonstrated favorable CO2/N-2 selectivity (19), high isosteric heat (20-42 kJ/mol) and stable cycling property. This work is designed to provide detail guidance and insights for carbon capture by heteroatom-doped biomass carbon.