SPECIATION OF HETEROATOMS IN COAL BY SULFUR-SELECTIVE AND NITROGEN-SELECTIVE TECHNIQUES

The peroxyacetic acid oxidation products from a series of coals of org anic sulfur content 0.5-9.8 wt% were examined. The distributions of or ganic S and N compounds were determined by gas chromatography with sul fur-selective flame photometric and nitrogen-selective thermionic spec ific detection respectively. A selected sample was also examined in gr eater detail using low-voltage high-resolution mass spectrometry. The distribution of organic sulfur compounds in the oxidation products was remarkably similar for all the coals. The number of sulfur compounds detected was small compared with that of organic nitrogen compounds de tected. This suggests that the sulfur chemistry of coal is considerabl y simpler than its nitrogen chemistry. Analysis of the m.s. data, toge ther with a comparison of sulfur-selective and nitrogen-selective chro matograms, indicated that a significant proportion of the heteroatomic species present in coal contain more than one heteroatom. This is sig nificant, because few models of coal structure incorporate such specie s.