Petroleum and coal tar pitches have been treated thermally at 400 degreesC
and 470 degreesC, extracted with toluene and subsequently activated with CO
2 at 900 degreesC. With one exception, the development of the micropore wid
ths and volumes in the resulting carbons follows the trend observed for car
bons based essentially on precursors of vegetable origin. On the other hand
, petroleum pitch treated at 400 degreesC leads to an active carbon which f
ollows the pattern observed for cokes, semi-cokes and pyrolyzed tyres. It i
s suggested that the difference between the two types of active carbons is
due to the large amount of compounds with low molecular weight left in the
petroleum pitch after thermal soaking. (C) 2001 Elsevier Science Ltd. All r
ights reserved.