Removal of elemental mercury in flue gas by Cu-Fe modified magnetosphere from coal combustion fly ash

Li, Yang; Dang, Lixin; Yang, He; Li, Jie; Hu, Haoquan

doi:10.1016/j.fuel.2020.117668

Cited by 19 publications

(5 citation statements)

References 44 publications

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“…Similarly, Chen et al 82 and Yang et al 83 investigated the effect of SO 2 on the Hg 0 capture performance of Fe−C-3 and Fe 2 MnO 4 /CNF adsorbents and found that SO 2 had a inhibition effect on Hg 0 capture. Yang et al 105 and Li et al 112 also suggested that SO 2 played a negative role in Hg 0 removal. These results were consistent with the research of Yang et al, 88 who found that SO 2 would reduce the Hg 0 removal efficiency of magnetic adsorbents (CuFe/ WSWU).…”

Section: Effects Of Nomentioning

confidence: 99%

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Review on Magnetic Adsorbents for Removal of Elemental Mercury from Flue Gas

2020

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Mercury in flue gas has been identified to be one of the most harmful environmental pollutants to humans and other organisms as a result of its bioaccumulation, volatility, persistence, high toxicity, etc. Although many adsorption removal technologies have been developed to control mercury emissions, they are difficult to be used in practical industrial applications as a result of their own technology and cost constraints. Thus, more efficient and low-cost mercury pollution control technologies need to be further developed. Because of its good adsorption performance, easy separation and recovery, low toxicity, and high chemical stability, magnetic adsorbents are considered as one of the most promising adsorbents for controlling mercury emissions in flue gas. This review mainly analyzes the latest developments and research progress in the removal of Hg 0 in flue gas by magnetic adsorbents, especially magnetic iron-based adsorbents, magnetic carbon-based adsorbents, magnetic fly-ash-based adsorbents, and magnetic mineral-based adsorbents. The Hg 0 removal performance, mechanism, and kinetics of magnetic adsorbents are reviewed. The effects of flue gas compositions (such as O 2 , NO, SO 2 , CO 2 , H 2 O, etc.) on Hg 0 capture performance are summarized. The merits and drawbacks of magnetic adsorbents for capturing Hg 0 and the future development directions are also discussed. In comparison to other adsorbents, magnetic adsorbents can be easily separated from fly ash as a result of their better magnetization characteristics. It was found that the MoSe x (inter)Fe 3 O 4 adsorbent showed good Hg 0 removal performance, and the capacity of Hg 0 removal was up to 135 mg/g. In addition, considering the entire life cycle, magnetic adsorbents are more attractive in costs than other common adsorbents. The development and design of the magnetic adsorbents, which possess high adsorption efficiency, simple and efficient separability, green sustainability, good regeneration ability, and low production cost, are considered to be one of the research hotspots in the future. The purpose of this work is to provide theoretical guidance for the further development of magnetic adsorbents in the field of mercury control.

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Section: Effects Of Nomentioning

confidence: 99%

“…Li et al 112 developed a Cu−Fe-modified magnetosphere adsorbent by the sol−gel method to remove Hg 0 . The results indicated that the Cu−Fe-modified magnetosphere adsorbent derived from fly ash exhibited excellent Hg 0 capture performance at 200−350 °C.…”

Section: Hg 0 Removal Performance Of Magnetic Adsorbentsmentioning

confidence: 99%

Review on Magnetic Adsorbents for Removal of Elemental Mercury from Flue Gas

2020

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“…It is reported that , the occurrence of the most Fe in PCFA was as magnetite, which could be separated by the magnetic separation method, and about 70% of Fe could be removed after a direct magnetic separation. However, most of the Fe in CFBFA exists mainly as hematite (α-Fe 2 O 3 ) with weak ferromagnetic properties, − and it is difficult to remove Fe from CFBFA efficiently by direct magnetic separation.…”

Section: Introductionmentioning

confidence: 99%

Spinel Ferrite Transformation for an Efficient Fe Removal from Circulating Fluidized Bed Fly Ash by Carbothermal Reduction at a Low Temperature

Gao

Wang

et al. 2022

ACS Omega

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Alumina (Al 2 O 3 ) extraction from circulating fluidized bed (CFB) fly ash (CFBFA) is one of the most important pathways for value-added utilization. However, in CFBFA, impurity iron (Fe) normally coexists, resulting in complicated separation processes, low Al 2 O 3 extraction efficiency, and substandard Al 2 O 3 -based products. How to remove Fe impurity effectively from CFBFA has become an important issue. For an effective Fe removal from CFBFA, spinel ferrite transformation by carbothermal reduction at a low temperature was discussed in the paper. The effects of the reduction temperature and reduction time on the removal efficiency of Fe and the recovery of aluminum (Al) as well as the removal of other metals were systematically investigated, and the transformation mechanisms of Fe-containing phases were investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and a scanning electron microscope–energy dispersive spectrometer. The results showed that Fe in CFBFA was present in the form of weakly magnetic α-Fe 2 O 3 , leading to a Fe removal of about 17.1% after magnetic separation; however, the recovery efficiency of Al reached 97.4%. Weakly magnetic hematite (α-Fe 2 O 3 ) could be converted to strongly magnetic spinel-type ferrite (MFe 2 O 4 ) after carbothermal reduction at 700 °C for 60 min, and the Fe removal efficiency could reach 62.8% after magnetic separation; however, the recovery of Al was 81.2%, which was decreased compared to the recovery of Al under the condition without carbothermal reduction treatment. However, the carbothermal reduction–magnetic separation process did not have a major effect on the existing form and leaching behavior of Al, Li, and Ga. Simultaneously, it could be observed that some transition metal elements such as Mn, Cr, and so forth could be enriched in spinel-type MFe 2 O 4 and removed after magnetic separation, which also provided a way for transition metal enrichment and extraction of transition metals from other tailings.

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“…The oxidation of Hg 0 on an SCR catalyst coupled with the absorption of the resultant Hg 2+ using wet desulfurization slurry is recognized as a promising method for the removal of elemental mercury from flue gas, and this process does not require a specialized device. It has been reported that Hg 0 is oxidized to Hg 2+ using HCl across SCR catalysts. , The Hg 0 oxidation activity of catalysts also depends on the HCl concentration and temperature of the flue gas . Some types of coal include only a small amount of chlorine and, in such cases, the absence of HCl in the flue gas leads to unsatisfactory Hg 0 oxidation efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…It has been reported that Hg 0 is oxidized to Hg 2+ using HCl across SCR catalysts. 26,27 The Hg 0 oxidation activity of catalysts also depends on the HCl concentration and temperature of the flue gas. 28 Some types of coal include only a small amount of chlorine and, in such cases, the absence of HCl in the flue gas leads to unsatisfactory Hg 0 oxidation efficiency.…”

Section: Introductionmentioning

confidence: 99%

Effects of HCl and O₂ on Hg⁰ Oxidation in the SCR Catalyst

et al. 2021

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Elemental mercury oxidation during the selective catalytic reduction (SCR) process, combined with desulfurization scrubbing, is a promising method for removing mercury from coal-fired flue gas. Selective catalytic oxidation of Hg0 from flue gas during the SCR process has been widely proposed and investigated. Understanding the precise Hg0 oxidation mechanism of SCR catalysts is crucial for employing the corresponding enhanced measures. However, the effects of HCl and O2 on the SCR catalyst for Hg0 oxidation are still unclear, and further work is needed in this direction. In the current study, the effects of O2 and HCl on Hg0 oxidation over the SCR catalyst were investigated in a fixed-bed reactor. The results indicated that the SCR catalyst exhibited poor Hg0 oxidation performance in the range of 100–400 °C, and the highest oxidation efficiency was 39.12% in a 4% O2 + 40 ppm HCl atmosphere at 200 °C. An increase in the O2 concentration enhanced the Hg0 oxidation efficiency, while the promoting effect of HCl was limited to a concentration <40 ppm. The synergistic effects of O2 and HCl on Hg0 oxidation were evident, with corresponding removal efficiencies of 39.12 and 31.69% at 200 and 350 °C, respectively. The Hg0 oxidation decreased significantly at high temperatures. Hg0 oxidation by O2 + HCl over the SCR catalyst occurred via the Eley–Rideal mechanism. Based on Hg0-TPD analysis, Hg0 oxidation products obtained on the surface were HgO and HgCl2.

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Removal of elemental mercury in flue gas by Cu-Fe modified magnetosphere from coal combustion fly ash

Cited by 19 publications

References 44 publications

Review on Magnetic Adsorbents for Removal of Elemental Mercury from Flue Gas

Review on Magnetic Adsorbents for Removal of Elemental Mercury from Flue Gas

Spinel Ferrite Transformation for an Efficient Fe Removal from Circulating Fluidized Bed Fly Ash by Carbothermal Reduction at a Low Temperature

Effects of HCl and O₂ on Hg⁰ Oxidation in the SCR Catalyst

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Removal of elemental mercury in flue gas by Cu-Fe modified magnetosphere from coal combustion fly ash

Cited by 19 publications

References 44 publications

Review on Magnetic Adsorbents for Removal of Elemental Mercury from Flue Gas

Review on Magnetic Adsorbents for Removal of Elemental Mercury from Flue Gas

Spinel Ferrite Transformation for an Efficient Fe Removal from Circulating Fluidized Bed Fly Ash by Carbothermal Reduction at a Low Temperature

Effects of HCl and O2 on Hg0 Oxidation in the SCR Catalyst

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Effects of HCl and O₂ on Hg⁰ Oxidation in the SCR Catalyst