Nanoporosity development in the thermal-shock KOH activation of brown coal

Thermal-shock KOH activation of brown coal (800 °C, KOH/coal ratio 1 g/g) was shown to produce nanoporous activated carbon with more developed surface area than thermally-programmed heating (SBET up to 1700 vs 1000 m2/g). Increasing the KOH/coal ratio (up to 1 g/g) in the activated mixture increases the total pore volume (0.14–1.0 cm3/g), the micropore volume (0.03–0.71 cm3/g), and also the volume of subnanometer pores (0.01–0.40 cm3/g). Thermal shock produces nanoporosity at lower KOH/coal ratios (0.5-1.0 g/g) than respective low-rate heating KOH activation.