Iron Oxide Based High Temperature Desulfurization Sorbent

Iron oxide sorbent is used as high temperature desulfurization sorbent due to high sulfur capacity, easy regeneration and recovery elemental sulfur. In this paper, the iron oxide based high-temperature sorbent was obtained by mixing iron oxide with calcium oxide, extrudating and calcinating. The sulfidation, reduction and regeneration performance for the prepared iron oxide based desulfurization sorbent were conducted. The phases of fresh iron oxide based sorbents, sulfided sorbent and regenerated sorbent were characterized by XRD and SEM. There are three reduced peaks corresponding Fe₃O₄, FeO and Fe for iron oxide based sorbent in temperature-programmed reduction. The breakthrough curve of iron oxide based sorbent in present of H₂ and H₂S at 500degC and 3600 h^-1 shows that outlet concentration of H₂S exhibits a peak at early stage, and then approaches a stable until breakthrough. This phenomenon shows that Fe₂O₃-H₂ reaction rate is more rapidly than Fe₂O₃-H₂S reaction. The Fe₂O₃ reacts rapidly with H₂ to form FeO and FeO reacts with H₂S to form FeS. This work examined the sulfur compound concentration change during regeneration as a function of temperature. The regeneration reaction is given by 2FeS + 7/2O₂ = Fe₂O₃ + 2SO₂ when O₂ take as the only reactive component in the feed gas, 3FeS + 4H₂O = Fe₃O₄ +3H₂S +H₂ when H₂O take as the only reactive component in the feed gas. The regeneration rate in O₂ is more rapid than that in H₂O, and there are big pore on the surface of the regeneration sorbent in oxygen agent compared with the regeneration sorbent in steam agent.