Preparation of N-doped hierarchically porous carbon from chitosan using molten salt method for efficient CO2 adsorption

Abstract

As a nitrogen rich and renewable biomass material, the preparation of N-doped porous carbon from chitosan offers an economically favorable and environmentally friendly approach. In the current work, we propose the synthesis of N-doped hierarchically porous carbon from chitosan using molten salt method. Chitosan was carbonized in liquid LiCl/KCl molten salt medium to synthesize the macroporous precursor, which was subsequently activated with KHCO₃ and urea. A hierarchically micro-meso-macroporous structure was constructed. The carbons were also characterized with multiple techniques to study the effects of different synthesis parameters. The obtained carbons showed large specific surface area (828–2658 m²/g) and tunable N content (1.77–10.77 wt%). CO₂ adsorption performances of the carbons were also systematically investigated. At 25 °C and 1 bar, a high CO₂ uptake of 4.10 mmol/g was achieved by the sample prepared at 700 °C. The carbons also showed high CO₂/N₂ selectivity, and excellent adsorption stability. The current study indicates that the obtained N-doped hierarchical carbon has great potential in CO₂ adsorption applications.