Activated carbon produced from an Illinois Basin coal

Abstract

Activated carbons were produced from an Illinois Basin bituminous coal (IBC-106) by a three-step process: oxidation of the coal in air at 150–250 °C for 2–40 hours, devolatilization of these oxidized coals in nitrogen at 500–730 °C for 1 hour and activation (gasification) of the chars in 45% steam, 4% oxygen in nitrogen at 730–880 °C for 3.5–96 hours. Products were characterized in terms of CO 2 single-point BET surface area, helium and bulk densities, pore volume and toluene adsorption capacity. Seven of the nine carbons produced had surface areas exceeding 1000 m 2 g −1 (dry). It was confirmed that the application of oxidation pretreatment eliminates the caking of IBC-106, preserves the coal's microstructure, and leads to high carbon surface areas. In comparison with Darco coconut charcoal, a commercial activated carbon (Fisher Scientific) whose surface area was 547 m 2 g −1 (dry), the largest toluene adsorption capacity of activated carbons was 1.57 g g −1, four times more than that of Darco. Production costing analysis on a laboratory scale suggested that, in a single production run, the most cost-effective final product is not the activated carbon with maximum surface area but the carbon produced at the lowest cost for each square meter of pore surface area.