Etude par resonance paramagnetique electronique des goudrons de pyrolyse rapide

An ESR investigation was made of coals and of the corresponding tars produced by rapid pyrolysis and trapped at 100°K in the resonant cavity of a spectrometer. The coals give rise to an ESR signal which can be resolved into a broad and a narrow line. New information was obtained from the saturation curves: the paramagnetic centres responsible for the narrow line are located in inertinite; the width of the broad line increases from vitrinite to exinite. The tars have a larger proportion of aliphatic compounds as compared with the original coal. This ‘renovation’ seems to be related to the complex depolymerisation and repolymerisation reactions during rapid pyrolysis. By reheating the tars from 100° to 400°K, one observes a gradual disappearance of the free radicals.