Electron transfer process: 1. Removal of organic sulphur from high sulphur Indian coal

Abstract

A novel experiment was carried out for the removal of organic sulphur from high sulphur Indian coal using the electron transfer process. The process involves initial formation of naphthalene radical anion by the interaction of naphthalene, dissolved in ethanol, with a metal ion (Cu+, Co2+, Ni2+, Sn2+ or Sb3+) of variable valence state which subsequently transfers electron to organic sulphur compound. A mechanism is proposed in which cleavage of C–S bonds occur by the metal naphthalenide forming soluble metal–organic sulphur compounds. Maximum amount of leached out sulphur is found to be 9.4% of the total organic sulphur with Sb3+ ion (without naphthalene) revealing that a particular type of organic sulphur was removed by this process. Aliphatic sulphur compound is believed to have leached out from coal and was found to be effective with metal ions having highly negative oxidation potentials. In case of metal ions with low negative oxidation potentials, e.g. Cu+ and Sn2+, although organic sulphur is removed, however, these ions rapidly form insoluble metal sulphides. This work provides a novel breakthrough of desulphurization of organic sulphur from coal.