School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China.
School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
J Environ Sci (China). 2022 Mar;113:141-151. doi: 10.1016/j.jes.2021.04.007. Epub 2021 Jul 12.
LnMnO (Ln = La, Pr, Nd, Sm, Eu, Gd or Dy) perovskites synthesized by sol-gel method were employed for gaseous elemental mercury (Hg) removal from coal-fired flue gas. Characterization results revealed the structure of the perovskites presented a phase transition process from rhombohedral system to O- and O'-orthorhombic structure with the change of A-site rare earth elements. The perovskites showed satisfactory Hg removal capacity in a narrow temperature range of 100-150°C. NdMnO with an O-O' orthorhombic structure presented the best Hg removal performance, which markedly depends on four factors: crystal structure, oxygen vacancy density, Mn/Mn ratio and surface element segregation. The Hg removal mechanism was illustrated based on the mercury temperature programmed desorption experiment and X-ray photoelectron spectroscopy characterization. Both chemisorption and catalytic oxidation played a role in the Hg removal process. Chemisorption dominated the Hg removal, due to the slow catalytic oxidation rate at low temperature. This work preliminarily established the relation between the structure of rare earth manganese perovskite and Hg removal performance.
采用溶胶-凝胶法合成了 LnMnO（Ln=La、Pr、Nd、Sm、Eu、Gd 或 Dy）钙钛矿，用于去除燃煤烟气中的元素汞（Hg）。表征结果表明，钙钛矿的结构经历了从菱面体系统到 O-和 O'-正交结构的相变过程，这与 A 位稀土元素的变化有关。在 100-150°C 的较窄温度范围内，钙钛矿表现出了令人满意的 Hg 去除能力。具有 O-O'正交结构的 NdMnO 表现出了最好的 Hg 去除性能，这主要取决于四个因素：晶体结构、氧空位密度、Mn/Mn 比和表面元素偏析。根据汞程序升温脱附实验和 X 射线光电子能谱的表征，阐述了 Hg 的去除机制。化学吸附和催化氧化在 Hg 的去除过程中都发挥了作用。由于低温下催化氧化速率较慢，化学吸附主导了 Hg 的去除。这项工作初步建立了稀土锰钙钛矿的结构与 Hg 去除性能之间的关系。
