Effect of coal preoxidation on the development of microporosity in activated carbons Original Research Article

Activated carbons have been prepared from a semianthracite preoxidised in air to different degrees. The activation has been carried out in steam at 850 °C to 50 ± 1% burnoff. The adsorption isotherms of nitrogen at 77 K and CO2 at 273 K have been determined. The adsorption isotherms indicate that the activated carbons obtained from non-oxidised coal has a poor porosity. The porosity increases with increase in the degree of coal preoxidation. The BET surface area increases from 160 m2g−1 in the case of activated carbon obtained from nonoxidised coal char to 847 m2g−1 for the activated carbon from oxidised coal char, t-plots obtained show that the degree of oxidation enhances both small and medium microporosity, the increase in small microporosity being much larger. The activated carbons obtained from preoxidised coal chars are largely microporous in character.