Production of elemental sulfur from spent sorbent and CO{sub 2}. Final report, April 1, 1992--October 31, 1994

This proof of concept project studied the feasibility of producing elemental sulfur from a spent solid sorbent and carbon dioxide (CO{sub 2}) gas. The objectives were to research (1) producing H{sub 2}S gas from an aqueous solution produced from spent sorbent solid consisting of primarily CaS, and (2) research the potential of producing elemental sulfur at temperatures below 600{degrees}C by means of a novel reaction between H{sub 2}S with CO{sub 2}. The spent sorbent derives from a novel coal desulfurization process currently under development by the Ohio Coal Development Office (OCDO) and the US DOE that provides for up to 80% desulfurization of the coal before combustion. The spent sorbent consists mainly of calcium sulfide with minor quantities of unreacted lime (CaO) and limestone (CaCO{sub 3}). In this study, CaS is dissolved in a solution of acetic acid forming a solution containing primarily hydrogen sulfide, calcium ions and acetate ions. The hydrogen sulfide is subsequently stripped from the solution by carbon dioxide (available from stack gas) and the H{sub 2}S-CO{sub 2} mixture is catalytically converted to form elemental sulfur. This conversion is aided by the reaction between CO{sub 2} and H{sub 2}(water-gas shift reaction) to produce water vapor and carbon monoxide