Coals are actively interacting with oxygen and halogens. The reaction of coal with at- mospheric oxygen or an adsorption of water molecules on its surface may appear at rooM temperature causing self-oxidation described as a spontaneous combustion of coal. The heat treated coal goes through a decomposition of the organic substances (pyroly- sis), giving rise to the existence of temporary fragments of molecules or free radicals [1]. The formation of free radicals during heating of coal was quite early considered and dis- cussed by many authors [2–5]. Free radicals that formed by bond cleavage are the main intermediates during coal pyrolysis. Thus the determination of characteristics of these radi- cals becomes as highly important as the reaction itself in the thermal decomposition or in the study of mechanism of compound evolution. Free radicals can be detected by EPR method if they are maintained at steady-state. Among the method advantages are included high sensitivity, non destructivity, minor dos- age and broad detection in the study of free radicals in coals. In the present paper the low temperature (up to 200 °C) treatment to the coal was exam- ined by the EPR spectroscopy.
CHARACTERIZATION STUDY OF COAL SPONTANEOUS COMBUSTION BY EPR SPECTROSCOPY
M. Sambuu;M. C. Mozzati;P. Galinetto;
2016-01-01
Abstract
Coals are actively interacting with oxygen and halogens. The reaction of coal with at- mospheric oxygen or an adsorption of water molecules on its surface may appear at rooM temperature causing self-oxidation described as a spontaneous combustion of coal. The heat treated coal goes through a decomposition of the organic substances (pyroly- sis), giving rise to the existence of temporary fragments of molecules or free radicals [1]. The formation of free radicals during heating of coal was quite early considered and dis- cussed by many authors [2–5]. Free radicals that formed by bond cleavage are the main intermediates during coal pyrolysis. Thus the determination of characteristics of these radi- cals becomes as highly important as the reaction itself in the thermal decomposition or in the study of mechanism of compound evolution. Free radicals can be detected by EPR method if they are maintained at steady-state. Among the method advantages are included high sensitivity, non destructivity, minor dos- age and broad detection in the study of free radicals in coals. In the present paper the low temperature (up to 200 °C) treatment to the coal was exam- ined by the EPR spectroscopy.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
