Surface sulfidation modification of magnetospheres from fly ash for elemental mercury removal from coal combustion flue gas

Feng, Xin; Xiao, Rihong; Zhao, Yongchun; Zhang, Junying

doi:10.1016/j.cej.2022.135212

Cited by 47 publications

(6 citation statements)

References 40 publications

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“…In addition to the Si 2p peak, it is observed on the surface of the modified samples after Hg 0 adsorption that there are new Hg 2+ peaks at 105.0 eV (WSW− UV/H 2 O 2 AOP), 101.9 eV (MSW−UV/H 2 O 2 AOP), and 105.1 eV (AC−UV/H 2 O 2 AOP). 5,13 This shows that mercury adsorbed on the surfaces of the modified samples exists in the form of bivalent mercury (Hg 2+ ), and the oxidation adsorption reaction of Hg 0 occurs on the tested modified sample surfaces.…”

Section: X-ray Photoelectron Spectroscopy (Xps) Analysismentioning

confidence: 92%

“…In the past 3 decades, a series of Hg 0 remediation technologies, mainly containing already existing air pollutant controlling devices, adsorption capture, catalysis, traditional oxidation, and advanced oxidation, have been applied to remove of Hg 0 from coal-burning flue gas. − ,− Among various methods, adsorption capture is recognized as a promising Hg 0 capture technology because it possesses a simple process flow and lower requirements of devices and does not produce waste liquid. − Among various common adsorption materials, carbon materials (e.g., activated carbon, biomass carbon, etc.) are widely used porous materials for adsorbing Hg 0 in coal-burning flue gas as a result of the developed porous structure. , However, a lack of active sites on the carbon material surface impedes the large-scale application of these carbon materials in the gaseous Hg 0 capture field. , Common modification methods for carbon materials, such as acid/alkali, sulfide, halide, metal oxide, etc., have shortcomings, such as high energy consumption, extreme operating conditions, and/or secondary pollution .…”

Section: Introductionmentioning

confidence: 99%

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Clean Modification of Carbon-Based Materials Using Hydroxyl Radicals and Preliminary Study on Gaseous Elemental Mercury Removal

et al. 2023

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Carbon-based materials (e.g., activated carbon and biomass carbons) are widely used porous materials for adsorbing gaseous Hg0 as a result of the developed porous structure. However, scarcity of active sites on the carbon-based material surface impedes its application. Existing mainstream modification methods (acid/alkaline substances, halides, sulfides, metal oxides, etc.) have deficiencies relating to high energy consumption, extreme working conditions, and/or secondary pollution. In this work, hydroxyl radicals (•OH) produced by the photochemical advanced oxidation process (UV/H2O2 AOP) are used to modify three kinds of carbon-based materials (activated carbon, wheat straw biochar, and corn straw biochar) to form more oxygen-containing functional groups on carbon surfaces, and then these modified carbon-based materials are used to adsorb gaseous Hg0. The interaction between free radicals and the carbon surface, modification mechanism, and adsorption principle of Hg0 are preliminarily explored. The UV/H2O2 AOP can significantly raise the quantity of oxygen-containing functional groups on carbon surfaces, further resulting in the improvement of the Hg0 removal performance. The average Hg0 removal efficiencies of the three modified samples (WSW–UV/H2O2 AOP, MSW–UV/H2O2 AOP, and AC–UV/H2O2 AOP) are up to 90.59, 87.55, and 91.46%, respectively, which are significantly higher than those samples modified by UV or H2O2 alone (a new synergistic effect for modification is discovered). Chemically adsorbed oxygen (O*) and a C–O functional group are proven to play a vital important function in the adsorbing removal process of Hg0 over the tested modified samples.

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Section: X-ray Photoelectron Spectroscopy (Xps) Analysismentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Clean Modification of Carbon-Based Materials Using Hydroxyl Radicals and Preliminary Study on Gaseous Elemental Mercury Removal

et al. 2023

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“…In coal-fired flue gas, a significant amount of fly ash exists in flue gas. Some scholars have pointed out that unburned carbon and oxygen-containing functional groups in fly ash also have certain mercury removal capabilities [92,93]. Due to its relatively low cost, fly ash has the potential to be a promising mercury adsorbent.…”

Section: Adsorptionmentioning

confidence: 99%

Review on Mercury Control during Co-Firing Coal and Biomass under O2/CO2 Atmosphere

Lyu,

Xin

2024

Applied Sciences

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Combining biomass co-firing with oxy-fuel combustion is a promising Bioenergy with Carbon Capture and Storage (BECCS) technology. It has the potential to achieve a large-scale reduction in carbon emissions from traditional power plants, making it a powerful tool for addressing global climate change. However, mercury in the fuel can be released into the flue gas during combustion, posing a significant threat to the environment and human health. More importantly, mercury can also cause the fracture of metal equipment via amalgamation, which is a major risk for the system. Therefore, compared to conventional coal-fired power plants, the requirements for the mercury concentration in BECCS systems are much stricter. This article reviews the latest progress in mercury control under oxy-fuel biomass co-firing conditions, clarifies the impact of biomass co-firing on mercury species transformation, reveals the influence mechanisms of various flue gas components on elemental mercury oxidation under oxy-fuel combustion conditions, evaluates the advantages and disadvantages of various mercury removal methods, and finally provides an outlook for mercury control in BECCS systems. Research shows that after biomass co-firing, the concentrations of chlorine and alkali metals in the flue gas increase, which is beneficial for homogeneous and heterogeneous mercury oxidation. The changes in the particulate matter content could affect the transformation of gaseous mercury to particulate mercury. The high concentrations of CO2 and H2O in oxy-fuel flue gas inhibit mercury oxidation, while the effects of NOx and SO2 are dual-sided. Higher concentrations of fly ash in oxy-fuel flue gas are conducive to the removal of Hg0. Additionally, under oxy-fuel conditions, CO2 and metal ions such as Fe2+ can inhibit the re-emission of mercury in WFGD systems. The development of efficient adsorbents and catalysts is the key to achieving deep mercury removal. Fully utilizing the advantages of chlorine, alkali metals, and CO2 in oxy-fuel biomass co-firing flue gas will be the future focus of deep mercury removal from BECCS systems.

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“…Hg 0 reacts with gaseous oxidants such as Cl radicals, Cl 2 , HCl, and O 3 in the homogeneous oxidation process. , The heterogeneous oxidation process mainly removes Hg 0 by the Langmuir–Hinshelwood (L–H), Eley–Rideal (E–R), and Mars–Maessen (M–M) mechanisms. , The current research topic is to develop new catalysts with oxidation, low cost, and recoverability properties. Magnetic beads prepared from coal ash with magnetic properties modified by H 2 S could achieve 80% mercury removal efficiency at 150 °C . CuCl 2 -modified magnetic beads were injected into a 1000 MWth coal-fired unit, and mercury removal efficiency reached 85.78% .…”

Section: Introductionmentioning

confidence: 99%

“…Magnetic beads prepared from coal ash with magnetic properties modified by H 2 S could achieve 80% mercury removal efficiency at 150 °C. 47 CuCl 2 -modified magnetic beads were injected into a 1000 MWth coal-fired unit, and mercury removal efficiency reached 85.78%. 48 Due to the synergistic effect between different cations, the catalysts with spinel structure showed good performance in Hg 0 removal, and CoMn 2 O 4 spinel had a greater than 95% Hg 0 removal effectiveness at 40−160 °C.…”

Section: Introductionmentioning

confidence: 99%

Review and Perspectives of Mercury Removal by Spinel Compounds

Wang

Liu

et al. 2023

Energy Fuels

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Several preparation methods for current spinel compounds are briefly introduced. The effects of temperature and flue gas components on the removal of Hg 0 over spinel compounds are reviewed. The reaction processes and mechanisms of Hg 0 adsorption, oxidation, and desorption on the surface of spinel compounds are analyzed deeply. The current methods for improving Hg 0 catalytic oxidation performance by spinel-based photocatalytic materials are also introduced. There are two main types of spinel compounds for Hg 0 removal: conventional spinel and loaded spinel compounds. Loaded spinel compounds are favorable for the adsorption and oxidation of Hg 0 due to more active sites and a larger surface area than ordinary spinel compounds. Both O 2 and HCl contribute to Hg 0 removal with Hg 0 oxidation efficiency being sensitive to both O 2 and HCl concentrations. The presence of SO 2 has a detrimental effect on the removal of Hg 0 due to the competition for the active adsorption sites on the surface of catalysts and adsorbents. The impact of temperature is bidirectional, and an optimum temperature exists. Based on the analysis of three stages (adsorption, oxidation, and desorption) included in the Hg 0 catalytic oxidation process, it was discovered that for most catalysts the Hg 0 oxidation process is the rate-limiting step for the reaction.

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Surface sulfidation modification of magnetospheres from fly ash for elemental mercury removal from coal combustion flue gas

Cited by 47 publications

References 40 publications

Clean Modification of Carbon-Based Materials Using Hydroxyl Radicals and Preliminary Study on Gaseous Elemental Mercury Removal

Clean Modification of Carbon-Based Materials Using Hydroxyl Radicals and Preliminary Study on Gaseous Elemental Mercury Removal

Review on Mercury Control during Co-Firing Coal and Biomass under O2/CO2 Atmosphere

Review and Perspectives of Mercury Removal by Spinel Compounds

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