Development of activated carbons from coal and biomass combustion and gasification chars

The physical and chemical properties of coal and biomass chars derived from combustion and gasification processes, as well as their potential use as feedstock for activated carbons, were studied. Of the samples collected, the wood-based sample showed higher loss-on-ignition than the coal-based samples. The lignite-based commercial activated carbon, Darco FGD, contained 35% ash. The wood-based sample had a lower starting point for weight loss (180°-300°C vs. 200°-400°C) than the coal based char and its thermal reaction was more complex. Compared to the raw char (FA1 and GT), both activated char samples (FA1-30 and GTI-30) had much more developed porosity after the 30 min one-step activation process. The activated GT sample had surface area ≤ 564 sq m/g on a carbon basis, which is comparable to the commercial activated carbon FGD of 526 sq m/g. The mesoporosity of activated GT char was 56% on a surface basis or 73% on a volume basis, which is comparable to the commercial activated carbon FGD (53% is on a surface basis or 77% on a volume basis). Both samples have a porous structure containing a large amount of mesopores, suggesting that they have good mass transfer properties.