Journal of Analytical and Applied Pyrolysis 63 (2002) 223–239 www.elsevier.com/locate/jaap Pyrolysis behaviour of petroleum pitches prepared at different conditions M. Pe ´rez a , M. Granda a, *, R. Garcı ´a a , R. Santamarı ´a a , E. Romero b , R. Mene ´ndez a a Instituto Nacional del Carbo ´n, CSIC, C/Francisco Pintado Fe, 26, Apartado 73, 33080 Oiedo, Spain b Repsol Petro ´leo, S.A., Valle de Escombreras 30350 Cartagena, Spain Received 15 February 2001; accepted 16 May 2001 Abstract Three petroleum pitches were prepared by applying three different treatments to the same petroleum feedstock: (i) distillation, and (ii) two different thermal treatments. Pitch composi- tion was monitored by standard procedures (elemental analysis, solubility parameters, softening point (SP), carbon yield, etc.), and chromatographic (gas chromatography and high performance liquid chromatography), spectroscopic (Fourier transformed infrared spec- troscopy) and rheometric techniques. Pitch pyrolysis behaviour was studied by thermogravi- metric analysis (TG/DTG), differential scanning calorimetry (DSC) and optical microscopy of the pitch pyrolysis products obtained at 450 °C and pitch cokes. The results show that the preparation conditions affect the structure of pitch components considerably. Distillation gives rise to a high SP pitch enriched in alkyl- and aryl-substituted aromatic compounds. Pitches obtained by thermal treatments underwent a certain degree of polymerization and a substantial amount of the alkyl- and aryl-substituted aromatic compounds present in the petroleum feedstock were transformed into planar aromatic cata-condensed compounds. The pyrolysis behaviour of pitches clearly reflects the differences in chemical composition, and consequently, in the preparation conditions. In the pitch obtained by distillation, the weight loss and thermal phenomena associated with polymerization reactions are much more pronounced than in pitches obtained by thermal treatments. On the other hand, under the same experimental conditions, thermally treated derived pitches generate a higher amount and more developed mesophase than distilled derived pitch. Studies carried out by DSC in conjunction with optical microscopy revealed that the exothermal peaks observed on the * Corresponding author. Tel.: +34-985-11-9090; fax: +34-985-297-662. E-mail address: mgranda@incar.csic.es (M. Granda). 0165-2370/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0165-2370(01)00156-5