A PYROLYSIS-GAS CHROMATOGRAPHY MASS-SPECTROMETRY STUDY ON COALS

Various coals, including the complete set of Argonne Premium Coal Samples, have been characterized using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The addition of the GC step to Py-MS was found to significantly improve the separation, identification and quantitation of volatile pyrolysis products. The analytical results were found to be independent of the storage condition of the sample, since the Py-GC/MS results obtained from three samples (two coals from Poland and Colombia and a lignite from North Dakota, USA), that were not stored under controlled conditions, fit very well all the other data. A good correlation is shown between Py-GC/MS data and both carbon content and degree of aromaticity, which in turn represent the coal rank. Although high molecular weight and highly polar fragments are undetectable in these experimental conditions, the pyrogram consitutes a fingerprint for a given coal, containing information about its macromolecular structure.