Effect Mechanism of O2 and H2O on SO2 Conversion and Existence Form in Activated Coke

Activated coke flue gas desulfurization technology (FGD) which has the advantages of water-saving and pollutant recyclable utilization is considered the important development direction of FGD. In this paper, effect mechanism of O₂ and H₂O in simulated flue gas on SO₂ conversion and existence form in activated coke is studied through the methods of fixed bed and ion chromatography. The research results show that:O₂ makes some chemical adsorbed SO₂ be oxidized to SO₃ whose adsorption pattern is different from that of SO₂. The formation of SO₃ makes SO₂ adsorption active sites vacant and creates the conditions to further adsorb SO₂. SO₃ can react with H₂O (g) to H₂SO₄ (g). The condensation of sulfuric acid vapor promotes the reaction of SO₃ and H₂O (g), and further promotes the oxidation of SO₂. Increase of O₂ concentration can reduce the diffusion resistance and increase the probability of oxygen diffusion to the active sites, Excess H₂O (g) in flue gas forms excess water film which can plug the pores and flood active sites, and ultimately hinder the diffusion of SO₂ and O₂ to micropores. O₂ and H₂O are necessary in AC desulfurization process. Reaction of SO₃ and H₂O (g) and condensation of sulfuric acid vapor are the dynamic of AC desulfurization process. Oxidation reaction of chemical adsorbed SO₂ and O₂ is the rate controlling step of the whole process.