Kinetic study of heterogeneous mercury oxidation by HCl on fly ash surface in coal-fired flue gas

Yang, Yingju; Liu, Jing; Shen, Fenghua; Zhao, Lipeng; Wang, Zhen; Long, Yan

doi:10.1016/j.combustflame.2016.03.022

Cited by 74 publications

(32 citation statements)

References 40 publications

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“…Three forms of mercury are emitted during the coal combustion process: elemental (Hg 0 ), oxidized (Hg 2+ ) and particulate‐bound mercury (Hg P ). Hg 2+ and Hg P can be easily captured by the wet flue gas desulfurization and dust removal devices . However, Hg 0 is difficult to remove due to the high volatility and water‐insolubility.…”

Section: Introductionsupporting

confidence: 52%

Insights into the Inhibitory Effect of H₂O on Hg‐Catalytic Oxidation over the MnO_x‐Based Catalysts

Zhou

Leng

et al. 2019

ChemistrySelect

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MnOx‐based catalyst has been used for elemental mercury (Hg0) removal in the coal‐fired flue gas, but the H2O in the flue gas significantly inhibits its activity. Generally, it is believed the inhibitory effect is caused by competitive adsorption between Hg0/HCl and H2O. In this study, we found that the MnOx was also aged in the flue gas with high concentration of H2O. The results indicated that the catalysts would be aged by H2O. The characterization of the fresh and aged catalysts showed that the amount of Mn4+ and chemisorbed oxygen species decreased. H2O didn't inhibit HCl adsorption on the catalyst surface, but suppressed the formation of active chlorine species, which was active for Hg0 removal. Therefore, besides the generally known competitive adsorption mechanism, there should be other possible reasons to interpret the inhibitory effects of water vapor on Hg0 oxidation process.

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Section: Introductionsupporting

confidence: 52%

Insights into the Inhibitory Effect of H₂O on Hg‐Catalytic Oxidation over the MnO_x‐Based Catalysts

Zhou

Leng

et al. 2019

ChemistrySelect

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“…There are two kinds of mercury removal technologies after combustion: One is to spray activated carbon or other kinds of solid adsorbent to remove mercury (Olson et al, 2000;Presto and Granite, 2006); The other is the oxidation of mercury through catalysts in denitration equipment. Oxidized mercury is absorbed by wet desulfurization equipment (Yang et al, 2016;Luo et al, 2010;Zhou et al,2016;Li et al, 2015;. Han et al (2016) modi ed the activated carbon by Pd doping, Pd and Fe co-doping.…”

Section: Introductionmentioning

confidence: 99%

Mercury removal from coal combustion flue gas by pyrite-modified fly ash adsorbent

Wang

et al. 2022

Environ Sci Pollut Res

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Pyrite and y ash have certain advantages in adsorption and mercury oxidation. The pyrite-modi ed y ash (PY+AC-FA) mercury adsorbent was prepared by mixing pyrite (PY) with acid-modi ed y ash (AC-FA), which has better mercury removal effect than AC-FA. The experimental results of mercury adsorption show: when the reaction temperature is 50°C, the best doping proportion of modi ed y ash is 20wt%, the mass proportion of pyrite to acid modi ed y ash is 4:1, and the ue gas ow rate is 1.0L/min, the adsorbent has the best performance, and the adsorption rate of mercury reaches 91.92%. BET, XRD, SEM, TG-DSG and XRF were used to characterize these adsorbents. And the mechanism of mercury removal of pyrite-modi ed y ash adsorbent is inferred: Hg 0 is rst adsorbed on the surface of the adsorbent, and then oxidized to HgS by the active component FeS 2 in pyrite-modi ed y ash.

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“…Mercury (Hg), a global contaminant, has aroused great public concern due to its detrimental effects on humans and ecosystem health. − The Minamata Convention on Mercury entered into force to curtail mercury emission in August 2017. , Therefore, more joint efforts should be mounted in Hg mitigation. Mercury species in flue gas generally exist in three forms: − elemental mercury (Hg 0 ), oxidized mercury (Hg 2+ ), and particulate-bound mercury (Hg p ).…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Landscape of HCl-Mediated Hg⁰ Capture by Magnetite

et al. 2019

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Magnetic sorbents for elemental mercury capture from flue gas have received considerable attention due to their high efficiency as well as magnetic and regenerable properties. Magnetite (Fe 3 O 4 ) is one of the main ingredients of magnetic sorbents. Firstprinciples calculations were conducted to provide an atomic-level mechanism of HCl-mediated Hg 0 reaction over magnetite. The Fe tet1 termination of Fe 3 O 4 (111) is the thermodynamically favored surface of Hg 0 adsorption. Hg 0 prefers to chemically adsorb on the iron active sites; the energy released from Hg 0 adsorption is 135.35 kJ/mol. The strong interaction of Hg 0 with active sites is mainly attributed to the atomic-orbital resonance of a Hg atom with a Fe atom. HCl adsorption over magnetite is a spontaneous dissociation reaction to generate activated chlorine species for HgCl 2 formation. HgCl serves as a key intermediate in Hg 0 transformation. Both HgCl and HgCl 2 undergo a strongly exothermic adsorption process. The nondissociative adsorption of HgCl 2 over magnetite is closely associated with the electron sharing between Fe and Cl atoms. The HCl-mediated mercury reaction over Fe 3 O 4 is controlled by the Langmuir−Hinshelwood mechanism. The energy barriers of the HCl-mediated Hg 0 reaction on the Fe tet1 -and Fe oct2 -terminal surfaces are 229.35 and 319.74 kJ/mol, respectively. The Fe tet1 termination is more active for the HCl-mediated Hg 0 reaction than the Fe oct2 termination. Hg* + Cl* → HgCl* is the rate-determining step of the comprehensive mercury reaction over magnetite.

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Kinetic study of heterogeneous mercury oxidation by HCl on fly ash surface in coal-fired flue gas

Cited by 74 publications

References 40 publications

Insights into the Inhibitory Effect of H₂O on Hg‐Catalytic Oxidation over the MnO_x‐Based Catalysts

Insights into the Inhibitory Effect of H₂O on Hg‐Catalytic Oxidation over the MnO_x‐Based Catalysts

Mercury removal from coal combustion flue gas by pyrite-modified fly ash adsorbent

Mechanistic Landscape of HCl-Mediated Hg⁰ Capture by Magnetite

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Kinetic study of heterogeneous mercury oxidation by HCl on fly ash surface in coal-fired flue gas

Cited by 74 publications

References 40 publications

Insights into the Inhibitory Effect of H2O on Hg‐Catalytic Oxidation over the MnOx‐Based Catalysts

Insights into the Inhibitory Effect of H2O on Hg‐Catalytic Oxidation over the MnOx‐Based Catalysts

Mercury removal from coal combustion flue gas by pyrite-modified fly ash adsorbent

Mechanistic Landscape of HCl-Mediated Hg0 Capture by Magnetite

Contact Info

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Resources

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Insights into the Inhibitory Effect of H₂O on Hg‐Catalytic Oxidation over the MnO_x‐Based Catalysts

Insights into the Inhibitory Effect of H₂O on Hg‐Catalytic Oxidation over the MnO_x‐Based Catalysts

Mechanistic Landscape of HCl-Mediated Hg⁰ Capture by Magnetite