Removal of trace sulfur dioxide from gas stream by regenerative sorption processes

This work compares the characteristics and SO₂ removal capacity of four physical adsorbents (sillicalite, DAY zeolite, polymer and carbon) and a chemical adsorbent (CuO/γ-Al₂O₃) prepared in our laboratory by a sol-gel process. SO₂ sorption capacity and kinetics of CuO/γ-Al₂O₃, silicalite and DAY zeolite were measured gravimetrically and compared with those of the polymer and carbon adsorbents reported in the literature. The sol-gel derived granular CuO/γ-Al₂O₃ adsorbent has the characteristics of large surface area, high crush strength and attrition resistance, and good sulfation properties. Simulated SO₂ breakthrough curves from a fixed-bed adsorber packed respectively with each of the five adsorbents are presented to examine the performance of these adsorbents for SO₂ removal in the fixed-bed process. Among the four physical adsorbents silicalite exhibits the best properties in terms of adsorption capacity and breakthrough time. Simulated and experimental results show that a fixed-bed packed with a chemical adsorbent (CuO/γ-Al₂O₃) is far more effective (with much longer breakthrough time) than that with a physical adsorbent (silicalite) for removal of trace SO₂ from gas stream.