Effect of H₂-regeneration on SO₂ removal activity of V₂O₅-CoO/AC

Elemental sulfur can be produced simultaneously during H₂-regeneration of SO₂-adsorbed V₂O₅-CoO/AC catalyst-sorbent when effluent gas of the regeneration is recycled back to the reactor. SO2 removal activities of the catalyst-sorbents after the regeneration under different conditions were studied in detail. It is found that elemental sulfur production requires transformation of sulfur forms between the solid phase and the gas phase, which results in residual sulfur in the catalyst-sorbent and a decrease in the subsequent SO₂ removal activity. The residual sulfur occupies a portion of micro-pores of V₂O₅-CoO/AC and increases its surface acid amounts. Both of them can be attributed to the decrease in SO₂ removal activity. H₂ purge after the regeneration is effective for converting the residual sulfur to H₂S and increasing the SO₂ removal activity. NH₃ treatment after the regeneration is also helpful to improve the SO₂ removal activity.