Microporous activated carbon aerogels via a simple subcritical drying route for CO2 capture and hydrogen storage

Abstract The successful synthesis of carbon aerogels, via a simple subcritical drying route and subsequent activation to high surface area carbons with attractive properties for gas storage is demonstrated. The route generates highly microporous carbon aerogel with a surface area of 508 m 2 /g and pore volume of 0.68 cm 3 /g wherein micropores account for 80% (407 m 2 /g) of surface area. The carbon aerogel is dominated by micropores of size 2 /g and pore volume up to 2.03 cm 3 /g. Activation at 600, 700 or 800 °C (and KOH carbon ratio of 2, 4 or 5) yields activated carbon aerogels with micropore size distribution centred at ca. 8 and 13 A (i.e., similar to that of the starting carbon aerogel) but with a large increase in pore volume arising from the micropores with the effect that pores of size 2 uptake of 2.7–3.0 mmol/g at 25 °C and 1 bar, and store between 3.5 and 4.3 wt% hydrogen at −196 °C and 20 bar. The hydrogen storage density of the carbons is high (up to 16.2 μmol H 2  m −2 ) with small micropores favouring high density.