Flash pyrolysis of coals. A new approach of classification

Flash pyrolysis—gas chromatography/mass spectrometry constitutes, in combination with statistical methods such as principal component analysis (PCA) and hierachical cluster analysis (HCA), an advantageous technique in an attempt to characterize and classify coals of different origin. Eight coals comprising three from South Africa, two from Australia, and one from U.S.A., Columbia and Indonesia, respectively, have been pyrolyzed at 750 °C.

Observed differences in the composition of the pyrolyzate have been elucidated by studying nine parameters: 1. (A) the content of long-chain aliphatic compounds; 2. (B) the content of benzene; 3. (C) the content of toluene; 4. (D) the content of toluene in the aromatic fraction; 5. (E)the content of naphthalene relative to the content of benzene + naphthalene; 6. (F) the content of cresols in the aromatic fraction; 7. (G) the content of cresols relative to the content of toluene + cresols; 8. (H) the content of o-cresol in the cresol fraction; and 9. (I) the content of styrene relative to the content of naphthalene + styrene. The data obtained have been treated statistically by means of PCA and HCA, demonstrating a high degree of similarity between the three South African coals, whereas a somewhat less pronounced similarity between the Australian coals was shown.The results are discussed based on an analogous study applying conventional coal analyses such as elemental analysis, maceral composition, vitrinite reflectance, ash content, etc.

A further comparison with studies applying ash composition data has been included.