Epr studies of thermal decomposition of exinite and inertinite

Exinite and inertinite from Polish medium-rank coal (85.6 wt%C) heated in inert atmosphere at 300-650 degrees C were investigated by electron paramagnetic resonance in the X-band (9.3 GHz). Numerical analysis of the line-shape of the e.p.r. spectra was performed. The g-factor, the linewidth of the components and their fraction in the total spectrum were determined. Three groups of paramagnetic centres with one Gauss and two Lorentz lines were detected for exinite. The e.p.r. spectra of inertinite were two superimposed Lorentz lines. During thermal decomposition the paramagnetic centres of exinite with broad Gauss and broad Lorentz lines and all the paramagnetic centres of inertinite were very active. The total concentration of paramagnetic centres in exinite considerably increased from 550 to 600 degrees C and decreased at 650 degrees C. A visible decrease in total concentration of paramagnetic centres in inertinite began at 500 degrees C. The microwave saturation of all the measured e.p.r. lines depended on the heat-treatment temperature. Copyright (C) 1996 Elsevier Science Ltd.