Effect of Ferric Oxide on the High-Temperature Removal of Hydrogen Sulfide over ZnO-Fe₂O₃ Mixed Metal Oxide Sorbent

The effect of ferric oxide on the removal of hydrogen sulfide over ZnO-Fe₂O₃ mixed metal oxide sorbents and on the oxidative regeneration of sulfided sorbents was investigated. When ferric oxide was added to the zinc oxide, the reduction of ZnO was retarded by interaction of ZnO with ZnFe₂O₄. This interaction was confirmed by larger binding energies of Zn 2p_3/2 and Zn 2p_1/2, identified by ESCA, of the ZnO-ZnFe₂O₄ sorbent than those of ZnO. Zinc ferrite with a spinel structure yielded not only high H₂S removal capacity but also much SO2 generation. A linear increase of SO₂ generation was confirmed up to 50 wt % Fe₂O₃. Resulting from the thermal decomposition of H₂S over metal sulfides, H₂ generation increased with respect to Fe₂O₃ according to a quadratic equation. Channeling, caused by sintering during sulfidation, made the flow path of the reactant change and thus pure ZnO sorbent and the sorbent containing 3 wt % Fe₂O did not sulfurate completely. Addition of Fe₂O₃ prevented surface structural change like sintering of ZnO during sulfidation.