Effect of CO₂/H₂O on adsorptive removal of H₂S/SO₂ mixture

Few studies focus on the simultaneous removal performance and mechanism of H₂S and SO₂ mixture in Claus tail gas with a high concentration of H₂O (20-30 vol.%) and CO₂ (8-10 vol.%). In this paper, the effects of H₂O and CO₂ on the simultaneous removal of H₂S and SO₂ for the by activated carbon (TL-1) were studied. Fresh (TL-1-F) and desulfurisation sulfur-loaded TL-1 activated samples (TL-1-E1 and TL-1-E2) were characterised by BET, elemental analysis, TG-MS, FT-IR and XPS. The simultaneous adsorption mechanism of H₂S and SO₂ on TL-1 in the presence of H₂O and CO₂ was discussed. Results show that the breakthrough sulfur capacity of TL-1 for the simultaneous removal of H₂S and SO₂ mixture reaches up to 301.6 mg S/g _ads when the feed gas containing 30 vol.% H₂O and 8 vol.% CO₂, which is 40% higher than that without H₂O. H₂O in the feed is adsorbed on the surface of TL-1 and forms a water film. The adsorbed H₂S and SO₂ are dissolved and ionised in the water film, which is conducive to the adsorption removal of H₂S and SO₂ by TL-1 and the generation of sulfuric acid (55.8%) and S₈ (44.2%). Meanwhile, CO₂ is only physically adsorbed on the surface of TL-1, and does not participate in the chemical adsorption (or chemical reaction) for the removal sulfide process.