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 2p3/2 and Zn 2p1/2, 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.