Effect of pre-carbonization of petroleum cokes on chemical activation process with KOH

The influence of pre-carbonization of petroleum cokes on the properties of the activated carbon precursors and final carbons activated with KOH was investigated by using TG-DTG, FTIR, XRD, and BET techniques. TG-DTG study revealed the decomposition of volatile species and FTIR analysis identified the presence of C-O, C-O-C, C-O-H and some alkyl species on the surface of the precursors. XRD results indicated that a disorder occurred after the carbonization at 500 degrees C and an order happened gradually with increasing the temperature. The decreases in the BET surface area and N-2 adsorption capacity coincided with the reduction of the functional species on the precursor surface with the increase of the pre-carbonization temperature. These surface functional species were proposed to play a key role in the porosity development during the KOH activation. First, they reacted with KOH to form the intermediate C-O-K species, then the resultants further reacted with the carbon of the precursor, and finally developed the porous structure. As a result, the surface area and the pore size distribution of the activated carbon can be controlled by optimizing the conditions of the pre-carbonization and activation processes. (C) 2005 Elsevier Ltd. All rights reserved.