Effects of feedstock pre-drying on carbonization of KOH-mixed bituminous coal in preparation of activated carbon

Activated carbon samples of different porosities and other characteristic features have been prepared using bituminous coal-KOH feedstocks of different degrees of pre-drying. The feedstocks were subjected to thermogravimetric analysis from 30 to 1000 °C. Different weight loss profiles and carbon burnt-off were obtained. This was associated with different level of potassium intercalations in the coal matrix and concomitant different extent of reactions with carbon. Another set of feedstocks was carbonized at 600 or 800 °C to obtain samples of activated carbon. The activated carbons were characterized using BET surface area, SEM, FTIR and XRD. These reflected the effects of pre-drying on the products. The surface area and V_meso/V_micro ratio increase with increase in duration of pre-drying. XRD profiles indicated lower proportion of aromatic stacking in the sample with highest surface area (1994 m²/g) and V_meso/V_micro ratio (0.91) than in the other samples. The pre-drying could be used as a key variable for obtaining activated carbons of different porosities.