Transformation of mesophase pitch into different carbons by heat treatmentand KOH etching

Carbons with different physical structures were prepared from mesophase pit ch powders by heat treatment and KOH etching at temperatures up to 900 degr eesC. The crystallite size of the carbons derived from heat treatment of th e pitch was found to be small, and little porosity was created in these car bons. However, high-porosity carbons can be prepared from heat treatment of the pitch that has been impregnated with KOH. The present work has demonst rated that this KOH-etching method can produce carbons with surface areas a nd pore volumes as high as 2900 m(2)/g and 1.7 cm(3)/g, respectively, with high yields of approximate to 30 wt.%. The influence of different parameter s during the etching process, such as the etching temperature, residence ti me and KOH/pitch ratio, on the carbon yield and the surface characteristics has been explored. The porosity of the resulting carbons was found to incr ease with the etching extent to a maximum and then began to decrease upon f urther etching. The optimum conditions to produce high-porosity carbons wer e recommended. (C) 2001 Elsevier Science B.V. All rights reserved.