Capture of sulfur dioxide from Claus tail gas using fiber-like alumina-based adsorbents

摘要

This paper describes the preparation of alumina fibers doped with CaO, MgO and La₂O₃ and reports their use as SO₂ adsorbents. These materials were characterized using electron microscopy, powder X-ray diffraction and infrared analysis and were examined for their ability to capture SO₂ selectively from gas mixtures containing large quantities of H₂O, CO₂ and some O₂ at temperatures in excess of 353Â K. Overall, it was found that these adsorbents could remove SO₂ selectively and that they could be regenerated by treatment with an H₂S-containing gas at approximately 600Â K. Adsorption capacity was retained over several cycles. Fourier transform infrared analysis showed that SO₂ was adsorbed as free SO₂ and also in a combined form as sulfite and sulfate species. In the regeneration step, the adsorbed sulfur species were reduced to elemental sulfur and H₂S or were desorbed as SO₂. It is proposed that the chemistry described here could be applied to design of a process for capture of all sulfur species typically found in a Claus-based sulfur recovery system.