CHARACTERIZATION AND THERMAL REACTIVITY OF OXIDIZED ORGANIC SULFUR FORMS IN COALS

X-ray photoelectron spectroscopy (XPS) and sulphur K-edge X-ray absorption near edge structure spectroscopy (XANES) were used to define the transformations of organically bound sulphur forms during mild oxidation of three low pyrite coals, and the eight Argonne Premium coals. At the conditions studied (125-degrees-C, 5 days), both techniques indicate that aliphatic sulphides are selectively oxidized to sulphoxides and sulphones. In one case (Rasa) sulphonic acids were the major product of oxidation. Aromatic sulphur forms were relatively unreactive. The thermal reactivity of organically bound sulphur forms in oxidized coals was studied using a temperature programmed decomposition-mass spectrometry system coupled with XPS and XANES analysis of the solid reaction products. Hydrogen sulphide evolution from oxidized coals is suppressed relative to that evolved from unoxidized samples. sulphur dioxide evolves from oxidized samples and most oxidized sulphur forms are retained in the residues from thermal treatment.