N-enriched ACF from coal-based pitch blended with urea-based resin for CO2 capture

• Successfully preparation of N-enriched ACF from pitch and urea–formaldehyde resin.
• N in fibers is mostly quaternary and its content decrease with activation degree.
• N-fibers activated under mild conditions showed a CO2 uptake of 3.4 mmol CO2 g−1.
• Fibers with high CO2 adsorption rates and with good selectivity towards N2 and CO2.
• CO2 adsorption performance of ACF maintained during several cycles.

N-enriched activated carbon fibers were successfully prepared from a coal derived pitch blended with urea–formaldehyde resin. The mixture was melt-spun, stabilized, carbonized and activated with KOH, giving rise to microporous carbon fibers with high nitrogen content (up to 2.2%). Nitrogen functional groups were mostly identified as quaternary N, and the content in this nitrogen group decreased with the degree of activation. N-enriched fibers activated under mild conditions (KOH/fiber = 5/1) showed the highest CO2 uptake (3.4 mmol CO2 g−1 at 25 °C and 1 atm). Due to their high alkalinity, the N-enriched fibers showed high CO2 adsorption rates and good selectivities for CO2/N2 and CO2/CH4 separation. After saturation with CO2, the fibers could be easily regenerated and maintained their performance over several adsorption–desorption cycles.

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