13C CP/MAS n.m.r. study of changes in molecular mobility of a bituminous coal during desulphurization

Abstract

A bituminous coal has been treated with molten alkali at several reaction temperatures and for different lengths of time. The fate of pyrite and the organic sulphur functional groups during desulphurization was followed by the recently developed technique of temperature programmed reduction. From 13C CP/MAS n.m.r. it is clear that there is a good correlation between the obtained structural parameters, carbon aromaticity and the fraction of the non-protonated aromatic fraction, and the relaxation times T2* 1H. The increased mobility in the aromatic structures confirms that the organic matrix is strongly modified when a high sulphur reduction is obtained.