Organically bound sulphur in coal: A molecular approach

Abstract

A critical review of literature concerning the molecular characterization of low and high molecular weight organosulphur constitutents present in coal as well as a detailed analysis of organic sulphur compounds present in flash evaporates and pyrolysates of a suite of coals ranging in sulphur content and degree of coalification reveals that the structure of organosulphur constituents in coal is very similar to that of organosulphur constituents present in bitumen and kerogen of sediments and in petroleums. Based on extensive knowledge with respect to the origin, nature and fate of organosulphur constituents in sediments and oils it is concluded that organosulphur constituents in coal are generated in the early stages of diagenesis (i.e. peat stage) by reaction of H2S or polysulphides (HSx−) with functionalized precursors yielding organic mono-and polysulphide moieties and thiophenes and that by increasing coalification alkylated thiophenes are converted to alkylated benzo [b]thiophenes and dibenzothiopenes via cyclisation and subsequent aromatization reactions.