Sulfur Dioxide Capture by Heterogeneous Oxidation on Hydroxylated Manganese Dioxide

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• 作者：Haodong Wu ; Weimin Cai ; Mingce Long ; Hairui Wang ; Zhiping Wang ; Chen Chen ; Xiaofang Hu ; Xiaojuan Yu
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：June 7, 2016
• 年：2016
• 卷：50
• 期：11
• 页码：5809-5816
• 全文大小：507K
• 年卷期：0
• ISSN：1520-5851

文摘

Here we demonstrate that sulfur dioxide (SO₂) is efficiently captured via heterogeneous oxidation into sulfate on the surface of hydroxylated manganese dioxide (MnO₂). Lab-scale activity tests in a fluidized bed reactor showed that the removal efficiency for a simulated flue gas containing 5000 mg·Nm^–3 SO₂ could reach nearly 100% with a GHSV (gas hourly space velocity) of 10000 h^–1. The mechanism was investigated using a combination of experimental characterizations and theoretical calculations. It was found that formation of surface bound sulfate proceeds via association of SO₂ with terminal hydroxyls. Both H₂O and O₂ are essential for the generation of reactive terminal hydroxyls, and the indirect role of O₂ in heterogeneous SO₂ oxidation at low temperature was also revealed. We propose that the high reactivity of terminal hydroxyls is attributed to the proper surface configuration of MnO₂ to adsorb water with degenerate energies for associative and dissociative states, and maintain rapid proton dynamics. Viability analyses suggest that the desulfurization method that is based on such a direct oxidation reaction at the gas/solid interface represents a promising approach for SO₂ capture.