Desulfurization of coal model compounds and coal liquids. [M. S. Thesis; treatment with metallic sodium or sodium salts followed by distillation]

Abstract

Most U. S. coals contain sulfur concentrations that prevent their being burned without some form of sulfur removal. Current coal~cleaning technology can only remove the fairly reactive pyritic (inorganic) and aliphatic (organic) sulfur. A process which removes the more refractory hetero-aromatic sulfur can substantially increase the amount of coal reserves amenable to chemical cleaning. Sodium metal dispersions convert refractory model compounds into lighter desulfurized products and non-volatile sulfur-rich char. When treated with sodium, coal-derived solids show substantial desulfurization. The same treatment applied to coal-derived liquids, when combined with vacuum distillation of the reaction product, yields a desulfurized light distillate, an increase in absolute amount of distillate, and retention of sulfur in the vacuum residue. The presence of sodium in the residue allows fixation of the residual sulfur as Na 2 S0 4 upon combustion, eliminating production of S02 in the flue gas. Intimate contacting of sodium salts with high sulfur coal also fixes 97-99% of the sulfur as Na 2 S0 4 upon combustion. This technique takes advantage of the high energy available for carbon-sulfur bond cleavage during combustion and'the reaction of S02 to form Na 2 S0 4 to provide an inexpensive method for complete coal desulfurization. From S. Ergun, Chemical Coal Cleaning Processes (Ref. 44).