Open Access

ARTICLE

HCl-Induced Hg⁰ Transformation over CuMn₂O₄ Sorbent

Aijia Zhang, Yingju Yang, Jing Liu^*, Junyan Ding

State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China

* Corresponding Author: Jing Liu. Email:

(This article belongs to the Special Issue: Advancement of Understanding of PM_2.5 and Hg Emissions and Their Control Technologies for Cleaner Combustion)

Energy Engineering 2022, 119(2), 499-510. https://doi.org/10.32604/ee.2022.015504

Received 23 December 2020; Accepted 21 May 2021; Issue published 24 January 2022

Abstract

CuMn₂O₄ spinel has been regarded as a highly efficient sorbent for Hg⁰ capture from flue gas. The regenerability and recyclability of CuMn₂O₄ sorbent are mainly associated with the mercury speciation adsorbed on its surface. However, the effect mechanism of HCl on Hg⁰ transformation over CuMn₂O₄ sorbent is still elusive. Experiments were conducted to understand the effect of HCl on Hg⁰ transformation over CuMn₂O₄ sorbent. The results indicate that CuMn₂O₄ sorbent is a mesoporous material and possesses a good thermal stability. CuMn₂O₄ shows >95% Hg⁰ removal efficiency in a wide temperature window of 50–350°C. The favorable electron-transfer environment caused by the mixed valence states of Cu and Mn cations is responsible for the excellent Hg⁰ removal performance of CuMn₂O₄ sorbent. CuMn₂O₄ shows a higher Hg⁰ adsorption capacity of 4774.57 μg/g. Hg⁰ adsorption process over CuMn₂O₄ sorbent can be well described by the developed kinetic model. Hg⁰ removal efficiency of CuMn₂O₄ sorbent does not depend on the presence of HCl. Mercury species adsorbed on the CuMn₂O₄ sorbent in the presence of HCl mainly exist in the forms of HgO and HgCl₂O₈ · H₂O. HCl shows a significant effect on mercury speciation over CuMn₂O₄ sorbent. Most of HgO species will be transformed into HgCl₂O₈ · H₂O in the presence of HCl.

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