The use of tannin to prepare carbon gels. Part I: Carbon aerogels Original Research Article

Tannin–formaldehyde carbon aerogels were prepared based on organic gels obtained by sol–gel polymerisation of tannin with formaldehyde that have been dried with supercritical acetone and pyrolysed at 900 °C. Tannins drastically reduce the cost of the gels, typically by a factor five, and polymerise in a wide range of pHs, leading to porous carbonaceous materials whose mesopore fraction ranges from 57% to 78%. The surface area and the total porosity can be as high as 715 m2 g−1 and 95%, respectively. Pore volumes and micro-mesopore-size distributions are similar to those of much more expensive carbon aerogels derived from resorcinol–formaldehyde resin. However, more easily adjustable pore textures may be obtained using tannins as precursors.