Influence of anthracite pretreatment in the preparation of activated carbons

Chemical modification by HClO4 was used prior to physical gasification with CO2 to produce activated carbon from La Mure (France) anthracite. BET surface areas as high as 1600 m(2) g(-1) and a total pore volume of similar to 1 cm(3) g(-1) were obtained for this activated carbon. XPS studies have shown that a Dart of the chlorine had reacted with the anthracite, producing partial oxidation at low temperature. Contrary to all expectations, SEM images confirmed no exfoliation after thermal shock. The main effect of the chemical pretreatment is to reduce the time of physical activation. This reduction can be attributed to the creation of numerous channels in the anthracite macrotexture during chemical pretreatment and thermal shock. The accessibility of the inner surface of the anthracite to CO2 was increased, and was responsible for deep gasification of the anthracite. Finally, physical activation after chemical pretreatment led mainly to a microporous carbon with a significant amount of mesoporosity. (C) 1998 Elsevier Science Ltd. All rights reserved.