Determination of forms of organic sulfur in coal by step-wise oxidation with perchloric acid-ferric perchlorate mixture

摘要

Differentiation of organic sulfur forms in coal by step-wise oxidation with a mixture of perchloric acid (HClO_4) and ferric perchlorate (Fe(ClO_4)_3) was studied. Various organic sulfur compounds were oxidized with HClO4 solution containing Fe(ClO_4)_3, and the amounts of sulfate formed during reaction were measured. The compounds can be grouped into three categories according to their reactivities as follows: (1) easily oxidized ones, i.e. disulfides, for which almost all of the sulfur was converted to sulfate after oxidation, (2) less reactive ones including aliphatic sulfides, aliphatic and aromatic thiols (20-30% of sulfur in these compounds was oxidized to sulfate), and (3) relatively stable ones, i.e. thiophenes and aromatic sulfides, from which no sulfate was formed. Samples of Illinois No. 6 and Bevier coals were also reacted with HClO_4 solutions containing increasing concentration of Fe(ClO_4)_3. The organic sulfur in these coals could be differentiated into various groups according to their reactivities.