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

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 m(2)/g, total pore volumes in the range of 0.02-0.61 cm(3)/g, and micropore volumes in the range of 0.02-0.54 cm(3)/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 degrees C and p= 800 mmHg). The CO2 activated Kevlar (R)-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 (R)-derived CFs is the preservation of fiber morphology, which can be destroyed during KOH activation. (C) 2016 Elsevier Ltd. All rights reserved.