Inherent thermal regeneration performance of different MnO2 crystallographic structures for mercury removal

Ting Yao; Yufeng Duan; Teresa M Bisson; Rajender Gupta; Deepak Pudasainee; Chun Zhu; Zhenghe Xu

doi:10.1016/j.jhazmat.2019.04.006

Inherent thermal regeneration performance of different MnO₂ crystallographic structures for mercury removal

J Hazard Mater. 2019 Jul 15:374:267-275. doi: 10.1016/j.jhazmat.2019.04.006. Epub 2019 Apr 3.

Authors

Ting Yao¹, Yufeng Duan², Teresa M Bisson³, Rajender Gupta³, Deepak Pudasainee³, Chun Zhu⁴, Zhenghe Xu⁵

Affiliations

¹ Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, China; Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
² Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, China. Electronic address: yfduan@seu.edu.cn.
³ Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
⁴ Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, 210096, China.
⁵ Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada; Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China. Electronic address: zhenghe.xu@ualberta.ca.

PMID: 31009891
DOI: 10.1016/j.jhazmat.2019.04.006

Abstract

Manganese oxides with different crystallographic structures were investigated for gas-phase elemental mercury removal. The inherent thermal regeneration performance and mechanism of α- and γ-MnO₂ were studied. The manganese dioxides were found to possess a mercury removal efficiency of higher than 96% even after 120 min mercury exposure except for β-MnO₂ which removed much less mercury than Mn₂O₃. The α-MnO₂ was found to have a higher recyclability of mercury capture and better durability for regeneration than γ-MnO₂. During the first 1 h of exposure, α-MnO₂ showed an excellent mercury capacity of 128 μg/g over 5 regeneration cycles. While for γ-MnO₂, the mercury capacity of the fifth cycle was reduced to 68.74 μg/g, which is much lower than 131.42 μg/g for the first cycle. The microstructure of α-MnO₂ was maintained throughout regeneration cycles due to its capability to retain lattice oxygen. In comparison, γ-MnO₂ experienced reconstruction and phase transformation induced by oxygen vacancies due to lattice oxygen loss during regeneration process, leading to a degradation in mercury capture. The α-MnO₂ oriented composite was found to be better developed into a regenerable catalytic sorbent for mercury removal from flue gases of coal-fired power plants.

Keywords: Coal-fired power plants; Manganese oxides; Mercury removal; Oxygen loss; Regeneration performance.

Publication types

Research Support, Non-U.S. Gov't