The report describes the use of microwave energy and NaOH to remove pyritic and organic sulfur from several U.S. coals. Exposure times on the order of 1 minute at 1 atmosphere of inert gas can remove up to 85% of the sulfur with little or no loss in heating value of the coal. Data analysis suggests that sulfur is converted to water soluble sulfides (Na2S, Na2Sx) in the process and that sulfur conversion follows first-order reaction kinetics. The mechanism by which fast rates of desulfurization are accomplished is most probably related to the fast (and to some degree selective) in-depth heating of the bed. The activation of water, FeS2, and NaOH creates local volatilization, high temperature and pressure conditions which accelerate sulfur reactions before the coal has a chance to decompose. It is also quite possible that local non-equilibrium chemistry (as a result of localized discharge sites) plays a beneficial role.

Prepared for Environmental Protection Agency, Office of Research ad Development. Contract no. 68-02-2172, program element no. EHE623A. June 1978. Includes bibliographical references.