Deeply insight into the inhibition mechanism of SO2 on mercury oxidation over Mn/CNT: A DFT study

IF 3 3区化学 Q3 CHEMISTRY, PHYSICAL

Computational and Theoretical Chemistry Pub Date : 2024-10-14 DOI:10.1016/j.comptc.2024.114918

Bo Zhao , Xi Sun , Linbo Qin , Qiang Zhang , Zeli Wang , Wangsheng Chen , Jun Han

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Abstract

Mn/CNT is a kind of low temperature catalyst, which can effectively remove elemental mercury from flue gas at low temperature, but its mercury removal ability was significantly inhibited by SO₂. In this work, the inhibition mechanism of SO₂ was investigated by first-principle calculation based on density functional theory. Three different surfaces of Mn/CNT were constructed: MnO/CNT, MnO₂/CNT and Mn₂O₃/CNT, and the adsorption of Hg⁰ and SO₂ on these three surfaces were studied. It suggests that adsorption energy of Hg⁰ on MnO/CNT is the highest, which is −2.42 eV. Combined with the electron partial density of states (PDOS) after adsorption, SO₂ can compete with Hg⁰ for the same Mn active site on the catalyst surface during the adsorption process, and the adsorption capacity of Hg⁰ is weaker than that of SO₂. Oxidation path of Hg⁰ to HgO on the surface of Mn/CNT indicates that the generation of HgO needs to cross at least two energy barriers, with energies of 0.552 eV and 1.25 eV, respectively. However, when Hg⁰ was oxidized to HgO and adsorbed on the surface of Mn/CNT, SO₂ could reduce it to Hg⁰ again, generating SO₃ to block elemental mercury oxidation.

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深入探讨二氧化硫对 Mn/CNT 氧化汞的抑制机理：DFT 研究

Mn/CNT 是一种低温催化剂，可在低温条件下有效去除烟气中的元素汞，但其脱汞能力受到 SO2 的明显抑制。本文基于密度泛函理论，通过第一性原理计算研究了 SO2 的抑制机理。构建了三种不同的 Mn/CNT 表面：研究了这三种表面对 Hg0 和 SO2 的吸附情况。结果表明，Hg0 在 MnO/CNT 上的吸附能最高，为 -2.42 eV。结合吸附后的电子部分态密度（PDOS），在吸附过程中，SO2 可与 Hg0 竞争催化剂表面上相同的 Mn 活性位点，且 Hg0 的吸附能力弱于 SO2。Hg0 在 Mn/CNT 表面氧化成 HgO 的路径表明，HgO 的生成至少需要跨越两个能垒，能量分别为 0.552 eV 和 1.25 eV。然而，当 Hg0 被氧化成 HgO 并吸附在 Mn/CNT 表面时，SO2 可以将其再次还原成 Hg0，生成 SO3，从而阻止元素汞的氧化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Computational and Theoretical Chemistry CHEMISTRY, PHYSICAL-

CiteScore

4.20

自引率

10.70%

发文量

331

审稿时长

31 days

期刊介绍： Computational and Theoretical Chemistry publishes high quality, original reports of significance in computational and theoretical chemistry including those that deal with problems of structure, properties, energetics, weak interactions, reaction mechanisms, catalysis, and reaction rates involving atoms, molecules, clusters, surfaces, and bulk matter.