Polyfuran-Derived Microporous Carbons for Enhanced Adsorption of CO₂ and CH₄

Oxygen-doped microporous carbons were synthesized by chemical activation of polyfuran with KOH or ZnCl₂ at 600 and 800 °C. It was found that KOH preserves and ZnCl₂ eliminates the O–C functional groups in the activation process. The O-doped carbon activated with KOH at 800 °C exhibited a high CO₂ capacity (4.96 mmol g^–1, 273 K, 1 bar) and CH₄ adsorption capacity (2.27 mmol g^–1, 273 K, 1 bar). At 298 K and 1 bar, a very high selectivity for separating CO₂/N₂ (41.7) and CO₂/CH₄ (6.8) gas mixture pairs was obtained on the O-doped carbon activated with KOH at 600 °C. The excellent separation ability of the O-doped carbons was demonstrated in transient breakthrough simulations of CO₂/CH₄/N₂ mixtures in a fixed bed adsorber. The isosteric adsorption heats of the O-doped carbons were also significantly lower than those of MOF-74 and NaX zeolite. The O-doped microporous carbon adsorbents appear to be a very promising adsorbent for CO₂ capture from flue gas, biogas upgrading, and CH₄ storage.