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5672917 
Journal Article 
Aromatic hydrocarbons formation during coal pyrolysis 
Cypres, R 
1987 
Yes 
Fuel Processing Technology
ISSN: 0378-3820 
15 
C 
1-15 
English 
The present paper demonstrates that the exclusive aromatic character of high temperature tar, is not only due to the disappearance, by post-cracking, of the paraffinic fraction of primary tars, but that cracking reactions contribute to form mono- and polycyclic aromatics. Aromatisation of the neutral and acid oil fractions of low temperature tar, was studied. The main pathway to aromatic compounds formation is the Diels-Alder reaction on short chain olefins, mainly butadiene and propene. The olefins are formed by post-cracking reactions of long chain paraffins in the primary tars and of cyclopentadiene, which is one of the primary cracking products of the phenols. These mechanisms were demonstrated by the cracking of pure compounds to investigate their fate in the post-cracking reactions occurring during coal carbonization. N-decane was chosen as representative of long chain aliphatics and 1,3-butadiene, 1-butene and iso-butene for the short chain olefins. Phenols, labelled in specific position by carbon 14 and tritium, were cracked. Radiochromatography was used to determine the radio-active content of each of the cracking products. Cyclopentadiene and CO are the primary cracking products of phenols. Cyclopentadiene is not stable at phenols' cracking temperatures. Direct formation of naphthalene from cyclopentadiene was observed at temperatures as low as 550°C. Fragments of the cyclopentadiényl radical undergo Diels-Alder reaction to form light aromatics.