Oxidation mechanism of elemental mercury by HCl over MnO2 catalyst: Insights from first principles

Zhang, Bingkai; Liu, Jing; Yang, Yingju; Chang, Ming

doi:10.1016/j.cej.2015.06.056

Cited by 87 publications

(26 citation statements)

References 40 publications

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“…For the case of the MnO 2 crystal surface, we focused on the stable and preferentially exposed β-MnO 2 crystal (110) surface. It has been well established that in alkaline media the most thermodynamically stable state of this surface is full coverage with splitting H 2 O [43–44], and we took the most stable state as the initiation of ORR, as in Fig. S8f.…”

Section: Discussionmentioning

confidence: 99%

Manganese deception on graphene and implications in catalysis

Dong

Wang

et al. 2018

Carbon

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Heteroatom-doped metal-free graphene has been widely studied as the catalyst for the oxygen reduction reaction (ORR). Depending on the preparation method and the dopants, the ORR activity varies ranging from a two-electron to a four-electron pathway. The different literature reports are difficult to correlate due to the large variances. However, due to the potential metal contamination, the origin of the ORR activity from “metal-free” graphene remains confusing and inconclusive. Here we decipher the ORR catalytic activities of diverse architectures on graphene derived from reduced graphene oxide. High angle annular dark field scanning transmission electron microscopy, X-ray absorption near edge structure, extended X-ray absorption fine structure, and trace elemental analysis methods are employed. The mechanistic origin of ORR activity is associated with the trace manganese content and reaches its highest performance at an onset potential of 0.94 V when manganese exists as a mononuclear-centered structure within defective graphene. This study exposes the deceptive role of trace metal in formerly thought to be metal-free graphene materials. It also provides insight into the design of better-performing catalyst for ORR by underscoring the coordination chemistry possible for future single-atom catalyst materials.

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Section: Discussionmentioning

confidence: 99%

Manganese deception on graphene and implications in catalysis

Dong

Wang

et al. 2018

Carbon

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“…2-4. 22, [44][45][46] In these processes, the active oxygen (O*) in the catalysts played an important role, which could be replenished by gaseous O2 (React. 5).…”

Section: Mechanism Of Hg 0 Removal Over the Mn-based Scr Catalystsmentioning

confidence: 99%

Research on the Mechanism of Elemental Mercury Removal over Mn-Based SCR Catalysts by a Developed Hg-TPD Method

et al. 2019

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Using SCR catalyst to oxidize and remove elemental mercury (Hg 0) synergistically is a promising method for mercury emission control in coal combustion power plants and is currently attracting widespread interest. In this study, a developed mercury thermal desorption (Hg-TPD) approach, combined with other associated methods, was employed for identification of the mercury species in the Mn-based SCR catalysts that have been used for synergistic Hg 0 removal. The analysis results demonstrated the Hg 0 adsorption on the catalysts was a necessary process for the Hg 0 removal, though the SCR catalysts removed Hg 0 mainly through catalytic oxidation and the amount of the adsorbed mercury contributed only a little to the Hg 0 removal efficiency. And the essential adsorption process was mainly in the way of chemisorption. HgO was the prime species that was identified to form in the catalysts, and a little amount of adsorbed HgCl2, Hg(NO3)2 and Hg-OM was detected as well in the samples spent in the simulated coal-fired flue gases. O2, HCl, NO and high concentration of CO2 in the flue gas all promoted the adsorption capacity and the generation of related Hg compounds so that they were conductive to Hg 0 removal efficiency, while similar phenomenon was not emerged in the presence of SO2, NH3 and H2O and meanwhile the amount of adsorbed HgO was decreased so that the efficiency was inhibited. The mobility testing by sequential extraction procedure indicated most of the retained Hg belonged to the mobile fraction, which was in accordance with the identification results of the Hg-TPD analysis. The consequences of this research would create a better understanding of the Hg 0 removal mechanism over the Mn-based SCR catalysts and provide additional information on the disposal of the retired catalysts in the environment.

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“…Mercury (Hg) has gained extensive concern recently because of its toxicity to environment and human body . Although the concentration of gas‐phase Hg is very low in flue gas (~1–20 μg/m 3 ), coal‐fired power plants are still the largest anthropogenic Hg emission source considering their huge quantity and scale . Mercury exists in three main forms in flue gas, including elemental mercury (Hg 0 ), oxidized mercury (Hg 2+ ), and particle‐bound mercury (Hg p ) .…”

Section: Introductionmentioning

confidence: 99%

Investigation on elemental mercury removal and antideactivation performance of modified SCR catalysts

Cai

Wang

et al. 2018

Asia-Pacific J Chem Eng

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The ever-growing concern of mercury exhausted from coal-fired boiler is driving the requirement for using novel catalysts with stable Hg 0 removal efficiency. However, the influences of flue gas components on Hg 0 removal performance of modified and deactivated catalysts have been seldom investigated previously. The antideactivation ability of modified catalysts is still unclear. In this study, cerium (Ce) and zirconium (Zr) were utilized to modify the honeycomb V 2 O 5 -WO 3 /TiO 2 catalysts. Sodium (Na) was doped on the rudimentary and modified catalysts by impregnation method to obtain deactivated catalysts. Elemental mercury removal efficiency of the catalysts was measured using a lab-scale experimental system under various working conditions. Characterization of the catalysts was conducted to further analyze the mechanism of Hg 0 removal process. Physical adsorption plays an important role in Hg 0 removal over catalysts in the atmosphere of N 2 and O 2 . The introduction of SO 2 has an adverse effect on Hg 0 removal because of the competitive adsorption. NO and HCl motivate the Hg 0 removal through different mechanisms whereas NH 3 has little effect on the removal efficiency. Mars-Maessen mode could be responsible for the excellent Hg 0 removal performance and the splendid antideactivation ability of Ce-modified catalysts. The efficiency of Zr-modified catalysts is lower due to the decline of vanadium content.

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Oxidation mechanism of elemental mercury by HCl over MnO2 catalyst: Insights from first principles

Cited by 87 publications

References 40 publications

Manganese deception on graphene and implications in catalysis

Manganese deception on graphene and implications in catalysis

Research on the Mechanism of Elemental Mercury Removal over Mn-Based SCR Catalysts by a Developed Hg-TPD Method

Investigation on elemental mercury removal and antideactivation performance of modified SCR catalysts

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