A comparison of physical activation of carbon xerogels with carbon dioxide with chemical activation using hydroxides

Carbon xerogels synthesized with a fixed resorcinol/sodium carbonate molar ratio (R/C) were physically activated using CO2. The effect of activation temperature and activation time on the final properties of the activated carbon xerogels was evaluated. The specific surface area increases from ∼600 m2 g−1 to 2000 m2 g−1 and more by increasing the temperature and duration of the activation step. A comparison between physical activation with CO2 and chemical activation with hydroxides was also performed: it was found that both processes produce an increase of the micropore volume and specific surface area without altering the mesoporosity developed during the synthesis. However, chemical activation can lead to the development of the narrow microporosity mainly whereas, in physical activation, the widening of the narrow micropores takes place whatever the process conditions.