Effect of different oxidation treatments on the chemical structure and properties of commercial coal tar pitch B. Petrova, T. Budinova * , N. Petrov, M.F. Yardim 1 , E. Ekinci 1 , M. Razvigorova Bulgarian Academy of Sciences, Institute of Organic Chemistry, Sofia 1113, Acad. G. Bonchev Str. bl. 9, Bulgaria Received 12 January 2004; accepted 3 September 2004 Available online 18 October 2004 Abstract Different oxidation treatment was used for the increase of the softening point of a commercial coal tar pitch. H 2 SO 4 , HNO 3 , H 2 O 2 and air are selected as treatment reagents. These preliminary investigations show that the oxidation treatment of commercial coal tar pitch with different reagents at 160 °C and heat treatment to 250 °C causes considerable changes in the chemical composition of obtained pitches. This leads to increase of TI and QI fraction, and results in considerable increase in the softening point of the pitches. The yield of modified pitches is considerable in the case of treatment with H 2 SO 4 ,H 2 O 2 , and HNO 3 and lesser in the case of air blowing. The data obtained also indicate some differences in the composition and softening point of pitches obtained after mod- ification with different reagents. These differences could influence the applicability of the obtained pitches in the various areas of carbon material production. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: A. Pitch; B. Oxidation; D. Carbon yield 1. Introduction The unique properties of high performance C–C com- posites make them irreplaceable for some applications That is why a strong demand exists for these composites despite their tedious manufacture and resultant high cost [1]. Usually, carbonized or graphitized carbon bod- ies are expected to exhibit a low porosity and adequate mechanical properties. One of the main problems in reaching this goal is to control the properties of the bin- der pyrolysis product. Contradictory properties are re- quired from the C–C composites matrix precursors. On the one hand, it should be highly thermoplastic to achieve acceptable fluidity at temperatures of filler impregnation. On the other hand, the coke yield should be high in order to produce carbons with low porosity and high strength. Coal tar pitches are long since known to be excellent raw material in the carbon manufactur- ing industry because of their high carbon content, low price and ability to produce carbon with different char- acteristic structures and properties. Chemical composi- tion and physical properties of pitches, which in turn influence their transformation to carbons, are of great importance in controlling the properties of derived car- bons. Therefore, the pitch characteristics are of prime consideration [2,3]. The main disadvantages of commer- cially available pitches are low carbon yields and signif- icant pore volume after carbonization, which produces undesirable effects on the physical and mechanical properties of produced materials. Hence, suitable proce- dures to raise the softening point of the pitches are nec- essary in manufacturing processes. A number of pitch 0008-6223/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbon.2004.09.006 * Corresponding author. Tel.: +359 29606145; fax: +359 2 870 02 25. E-mail addresses: goriva@orgchm.bas.bg (T. Budinova), ekin- cie@itu.edu.tr (E. Ekinci). 1 Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, Ayazaga Istanbul 34469, Turkey. Fax: +0 212 285 29 25. Carbon 43 (2005) 261–267 www.elsevier.com/locate/carbon