99/03023 Gasoline additives—status and development

Abstract

This chapter describes the characterization and chemistry of organically bound sulfur during coal conversion. The characterization of oxidized organic sulfur forms resulting from mild coal oxidation and the subsequent thermal reactivity of these oxidized sulfur forms have not been extensively explored. The nature of oxidized organic sulfur forms can yield insight into the forms initially present. In a study described in the chapter, a large fraction of the sulfides initially present in the fresh coals was converted to oxidized forms, while thiophenic forms were relatively stable under these mild conditions. For Rasa coal, the dominant oxidation product was identified to be sulfonic acid. Pure compound work has shown that sulfonic acids can arise from the oxidation of disulfides or mercapatans, while sulfoxides and sulfones result from oxidation of sulfides.