Bimodal cellular activated carbons derived from tannins

New cellular activated carbons mainly derived from tannins and furfuryl alcohol are introduced and suggested as adsorbents and catalyst supports. They present a bimodal porosity, based on a highly porous, reticulated vitreous carbon backbone, whose micro/meso-porosity was developed by steam activation. The macroporosity corresponds to the connected network of cells whose average diameter is close to 250 μm. In contrast, the micro/meso-porosity is located at the inner surface of the cells and is thus fully and easily accessible. Consequently, much higher adsorption kinetics than for usual granular activated carbons are expected. A burn-off close to 30% was shown to be optimal for getting a high proportion of microporosity without complete loss of mechanical resistance. In these conditions, the surface area is close to 850 m² g⁻¹, thus similar to that of many commercial carbonaceous adsorbents.