H₂S Absorption Behavior of Calcium Ferrite Prepared in the Presence of Coal

Abstract

Calcium ferrite (CaFe 2 O 4 ) absorbents of hydrogen sulfide (H 2 S) for hot-gas cleaning were prepared in the presence of Yallourn coal (YL). Calcium and iron nitrates in aqueous solution were impregnated onto YL, which was then dried at 70 °C in vacuo and calcined at various temperatures in air. The performance of the absorbent was evaluated using a fixed-bed flow-type reactor that was equipped with a quadrupole mass spectrometer. The surface area of the YL char-loaded CaFe 2 O 4 (CaFe 2 O 4 /YL) was ca. 25 m 2 /g, and its value was the same order of magnitude as those of unloaded ferrites that had been prepared by a coprecipitation method. The morphological structures of CaFe 2 O 4 /YL showed a rough surface with a macroporous structure; however, the surface of unloaded ferrites prepared by the dry process and the coprecipitation method was smooth and flat. When the absorption behaviors of CaFe 2 O 4 /YL for H 2 S were measured at 500 °C, the absorption capacity of H 2 S with CaFe 2 O 4 /YL exhibited almost 100% of the stoichiometric amount of loaded metal species and could efficiently remove 4000 ppm of H 2 S to a level of <1 ppm under a space velocity of 2800 h - 1 .