Removal of Hydrogen Sulfide and Ammonia by Goethite-Rich Limonite in the Coexistence of Coke Oven Gas Components

Abstract

Hydrogen sulfide (H₂S) removal and catalytic ammonia (NH₃) decomposition performance of limonite in the presence of coke oven gas (COG) components has been studied in a cylindrical quartz reactor at 300–850°C under a high space velocity of 51000 h⁻¹ to develop a novel hot gas cleanup method. The H₂S removal behavior in 50% H₂/He depends on the temperature, with high performance observed at lower temperature. An investigation of the removal behavior of H₂S in the presence of COG components (CH₄, CO, CO₂ and H₂O) at 400°C reveals that CH₄ does not affect the removal performance. On the other hand, the coexistence of CO drastically decreases the H₂S removal performance. However, the addition of 5% H₂O to 50% H₂/30% CH₄/5% CO/He dramatically improves the H₂S removal performance, whereas the performance is low at 5% CO₂ with 50% H₂/30% CH₄/5% CO/He. In addition, the H₂S breakthrough curve strongly depends on the space velocity.

The limonite catalyst achieves almost complete decomposition of NH₃ in He at 850°C until 240 min. When the decomposition run is performed in the presence of COG components, the coexistence of 30% CH₄ deactivates limonite with significant formation of deposited carbon. On the other hand, the addition of 5% CO₂, 5% H₂O or 5% CO₂/5% H₂O to 50% H₂/30% CH₄/5% CO improves the catalytic activity without carbon deposition, and >99% conversion of NH₃ to N₂ is maintained until 240 min.