STRUCTURE AND REACTIVITY OF COALS - FIELD-IONIZATION MASS-SPECTROMETRY VIEWPOINT

Studies on structure and reactivity of coals are presented that have been conducted using pyrolysis-field ionization mass spectrometry (Py-f.i.m.s.) since 1985. Py-f.i.m.s. analyses of approximately 80 coals varying from lignite to high-rank bituminous are considered. The volatilization in the mass spectrometer yielded 10-50 wt% of coal organic material responsive to f.i.m.s. analysis. Molecular masses of the volatiles in general were in the range 50-650 u. No or only low-intensity mass signals were detected in the range 650-1450 u, which was the detection limit of the high-mass-resolution magnetic instrument at + 8 kV source potential. The studies contribute to an understanding of coal structure by providing molecular weight distributions and individual composition data for the two components of the volatilized material, i.e. innate molecular components of coal and products of thermal decomposition of macromolecular material. In the area of application to coal reactivity, specific attention is paid to the use of correlation analysis, which was applied to (1) Py-f.i.m.s. spectra of numerous coals and (2) analytical data that quantitatively characterized the capacity of the coal to react with an H-donor or to yield products of thermally induced reactions such as decomposition and condensation. High-resolution f.i.m.s. and pyrolysis-g.c.-m.s. of the correlated mass signals provided characteristics of the reactive species involved in the reactions in question.