Change in pore structure of active carbon with heat-treatment

Abstract

The pore structure of an active carbon made from coal by steam activation at 850°C was changed by heating in a nitrogen atmosphere in the range 1000–1600°C. The adsorption isotherms of carbon dioxide, n-butane, isobutane and carbon tetrachloride at 298°K were determined for heat-treated active carbons. The change in micropore volume with heat-treatment temperature was estimated using the Dubinin-Polanyi equation. The micropore volume estimated from adsorption of carbon dioxide, n-butane and isobutane did not show any appreciable change after heat-treatment up to 1100°C (from that of the starting active carbon), while micropore volume estimated from adsorption of carbon tetrachloride changed drastically to zero when the carbon was heat-treated at 1000°C. This may suggest a possibility of making the molecular sieve carbons from active carbons by only heat-treatment.