Elemental sulfur production during the regeneration of iron oxide high-temperature desulfurization sorbent

Abstract

The production of elemental sulfur instead of SO 2 during the regeneration of high temperature desulfurization sorbents will improve the efficiency of advanced power generation processes such as the integrated gasification combined cycle (IGCC). While much research is directed at developing zinc-based sorbents because of the favorable thermodynamics of the ZnO–H 2S reaction, SO 2 is the inevitable product from ZnS regeneration. Iron-based sorbents, although less efficient for H 2S removal, permit significant amounts of elemental sulfur to be formed during regeneration. A laboratory-scale fixed-bed reactor has been used to study the regeneration of FeS in steam-oxygen mixtures. The experimental results are interpreted on the basis of four simultaneous reactions. Oxygen reacts rapidly with FeS to produce SO 2 and Fe 2O 3. Steam reacts to give Fe 3O 4 and H 2S. Elemental sulfur is formed by the reaction between H 2S and SO 2, and additional O 2 is consumed in converting Fe 3O 4 to Fe 2O 3. The maximum yield of elemental sulfur, approximately 75% of theoretical, was achieved using a large H 2O-to-O 2 ratio (200-to-1) at the lowest feasible regeneration temperature (600°C), and using a small regeneration gas feed rate.