Nitrogen-Containing Porous Carbon Fibers Prepared from Polyimide Fibers for CO₂ Capture

Abstract

Nitrogen-containing porous carbon fibers with a large BET surface area (919–1625 m2/g) and pore volume (0.429–0.772 cm3/g) were developed from polyimide fiber, which was treated in the presence of potassium carbonate by one-step simultaneous carbonization/activation. The effect of carbonization temperature on the porous and chemical structure was monitored. The nitrogen contents of activated carbon fibers decreased with the treatment temperature, which varied in a range of 1.23–2.76 wt %. Compared with the unactivated fiber, the activated ones showed more ultramicropores with a volume of more than 0.279 cm3/g. An optimal activated sample exhibited an excellent CO2 uptake of 5.0 mmol/g at 1 bar and 25 °C, with an acceptable Henry’s CO2/N2 selectivity of 24. The ultramicropore played a predominant effect on the CO2 uptake capacity, while the nitrogen functionalities played a predominant effect on the CO2/N2 selectivity.