Evolution of porosity of activated carbon fibres prepared from pre-oxidized acrylic fibres

Abstract

Industrially pre-oxidized acrylic fibres were used to prepare activated carbon fibres (ACF). The results obtained show that pre-oxidation was effective in increasing the carbon yield during carbonization and reducing the reactivity of the char with CO2 during activation, making it possible to obtain ACF with high pore volumes, up to 1.15 cm3 g−1, with BET area of 2064m2 g−1, even without a prior laboratory stabilization step. By controlling the activation temperature over the range 700–1000 °C and the activation time over the range 15–4320 min it was possible to obtain a range of materials varying from those which contained mainly ultramicropores, with a high capacity for the capture of CO2, up to others with a broader distribution of pore sizes extending up to 4 nm. An interesting aspect of the results was the observation that the volume of ultramicropores was practically constant for different activation times and temperatures up to 900°C. The importance of different processes which may contribute towards the development of porosity during activation is considered in the light of the results obtained.