Developing microporosity in Kevlar®-derived carbon fibers by CO2 activation for CO2 adsorption

•CO2 activation preserved the fiber morphology of Kevlar®-derived carbon (KCF).•CO2 activation of KCF is suitable for achieving high CO2 uptake at ambient conditions.•KOH activation of KCF assures high benzene vapor uptake at ambient conditions.

A series of activated carbon fibers (CFs) has been prepared from Kevlar® by carbonization and subsequent CO2 activation. The resulting materials exhibited the specific surface areas in the range of 50–1240 m2/g, total pore volumes in the range of 0.02–0.61 cm3/g, and micropore volumes in the range of 0.02–0.54 cm3/g. The well–developed microporous structure resulted in very good CO2 adsorption properties; the best uptake was 6.58 mmol/g of CO2 (at 0 °C and p = 800 mmHg). The CO2 activated Kevlar®-derived CFs achieved better CO2 uptakes than analogous carbons activated in KOH, but the latter outperformed them in benzene adsorption. We concluded that almost exclusively ultramicroporous (w < 1 nm) CO2-activated CFs adsorbed more CO2 due to the presence of small micropores, whereas the KOH-activated carbons possessed larger micropores, which are essential for adsorption of benzene and related molecules. An additional advantage of the CO2 activated Kevlar®-derived CFs is the preservation of fiber morphology, which can be destroyed during KOH activation.

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