Elemental mercury removal from syngas by nano-ZnO sorbent

Zhou, Jinsong; Pan, Qi; Hou, Wenhua; You, Shulin; Gao, Xiang; Luo, Zhongyang

doi:10.1016/s1872-5813(14)60004-9

Cited by 19 publications

(7 citation statements)

References 8 publications

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“…Noble metal sorbents exhibit excellent Hg 0 removal capacity in broad temperature windows, but they are very expensive for large-scale applications . Some metal oxides, such as Fe 2 O 3 -, CeO 2 -, and ZnO-based sorbents, have demonstrated good performance on the removal of Hg 0 from syngas under low temperatures (<150 °C). − Nevertheless, the Hg 0 removal efficiency will be significantly decreased as the reaction temperatures increased to 200 °C. However, Hg 0 capture in syngas is expected at an elevated temperature (approximately 200 °C) to improve the overall thermodynamic efficiency for power generation gasification systems. , Therefore, it is significant to develop an effective adsorbent that is beneficial for Hg 0 capture at the temperatures required for syngas purification.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, MnO 2 -based sorbents have been identified as the promising Hg sorbents as a result of their excellent capture capability and long persistent activity on the removal of Hg 0 from coal-fired flue gas. − However, it is unclear whether MnO 2 can effectively remove Hg 0 from syngas because the reducing environment is not favorable for Hg 0 oxidation. In addition, during the coal gasification process, another toxic byproduct H 2 S is released along with mercury, and it has drawn much concern as a result of its higher content (0.2–1%) and harmful effects on equipment as well as the environment and human health . MnO 2 -based sorbents have also been found to be desulfurizers for the removal of H 2 S from syngas. − However, the adsorption mechanism of H 2 S on the MnO 2 surface is unknown.…”

Section: Introductionmentioning

confidence: 99%

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Effect of the Mechanism of H₂S on Elemental Mercury Removal Using the MnO₂ Sorbent during Coal Gasification

et al. 2017

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A combination of experiments and density functional theory (DFT) calculations was employed to investigate the detailed reaction mechanism of elemental mercury (Hg0) with H2S over a MnO2 surface. The MnO2 sorbent was prepared by a low-temperature sol–gel autocombustion method and used to capture Hg0 from simulated syngas. The experimental results show that MnO2 possesses superior Hg0 removal capacity; over 85% Hg0 removal efficiency is achieved in the temperature range of 80–200 °C. An appropriate concentration of H2S promotes Hg0 removal by forming active sulfur species on the MnO2 surface. The computational results indicate that Hg0 and HgS are chemically adsorbed on the MnO2 (110) surface, with the adsorption energies of −69.50 and −286.33 kJ/mol, respectively. H2S undergoes dissociative chemisorption on the MnO2 (110) surface and forms active sulfur species for Hg0 transformation. Both Eley–Rideal (E–R) and Langmuir–Hinshlwood (L–H) mechanisms are responsible for heterogeneous Hg0 reaction with H2S over MnO2. The E–R mechanism (7.16 kJ/mol) in which gaseous Hg0 reacts with active surface sulfur species is kinetically more favorable than the L–H mechanism (42.00 kJ/mol) as a result of its much lower energy barrier. After the Hg0 heterogeneous reaction, the most stable mercury compound of HgS formed on the MnO2 surface, which is verified by the temperature-programmed desorption and X-ray photoelectron spectroscopy experimental results.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of the Mechanism of H₂S on Elemental Mercury Removal Using the MnO₂ Sorbent during Coal Gasification

et al. 2017

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“…The synthetic Mn, Fe, and Cu/Al Cu‐containing materials displayed mainly grain aggregates. Usually, Magnesium‐ and zinc‐based LDHs exhibited better lamella character because these metal ions have an excellent ability to be incorporated into Al‐containing hydroxides compared to other cations . LDHs comprise binary ions presenting different valence states, implying that their specific structures depend on the M 2+ /M 3+ molar ratio.…”

Section: Resultsmentioning

confidence: 99%

Enhancement of Mercury Sorbent Using Metal Aluminate Carbonates with Chloride under Hydrothermal Conditions

Lin

2016

J Chinese Chemical Soc

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Mercury sorbents M–Al–CO3 (M=Mg2+, Mn2+, Fe2+, Cu2+, or Zn2+) were prepared by the coprecipitation of M2 + and Al3+ in an alkaline NaOH/Na2CO3 solution. The formation of a layered double hydroxide structure significantly enhanced Hg removal, uniquely with a suitable binder as a support. Both Hg(NO3 )2 and HgCl2 were used to perform the capture test. The calcined sorbent exhibited superior efficiency, particularly for materials having bivalent states of mixed oxide (MO), such as calcined Mn and Fe. Chloride ions effectively raised the mercury scrubber efficiency, regardless of the type of sorbent. The results show that synthetic sorbents can provide 96% removal of Hg at 200°C. In addition, a suitable binder such as TiO2 can be used as a support for dispersing metal oxides, which significantly decreases the MO content while maintaining a high equivalent capture capacity.

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“…To date, mercury sorbents have been mainly divided into four kinds: activated carbons (ACs), − noble metals, ,− metal oxides, ,, and metal sulfides. ,− AC, especially carbon modified by sulfur and halogens, is found to be an effective sorbent for the capture of Hg 0 . , However, the application of AC is limited by the narrow temperature windows. Some metal oxides, such as Fe 2 O 3 -based, CeO 2 -based, MnO 2 -based, and ZnO-based , sorbents, have demonstrated good performance on the removal of Hg 0 from syngas at low temperatures (<150 °C). Nevertheless, the Hg 0 removal efficiency will be significantly decreased as the reaction temperatures increased to 200 °C.…”

Section: Introductionmentioning

confidence: 99%

“…12,22 However, the application of AC is limited by the narrow temperature windows. Some metal oxides, such as Fe 2 O 3 -based, 23 CeO 2 -based, 7 MnO 2 -based, 2 and ZnObased 24,25 sorbents, have demonstrated good performance on the removal of Hg 0 from syngas at low temperatures (<150 °C). Nevertheless, the Hg 0 removal efficiency will be significantly decreased as the reaction temperatures increased to 200 °C.…”

Section: Introductionmentioning

confidence: 99%

Effects of Supports on Pd–Fe Bimetallic Sorbents for Hg⁰ Removal Activity and Regeneration Performance from Coal-Derived Fuel Gas

Yue

Liang

et al. 2019

Energy Fuels

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Pd–Fe bimetallic sorbents were shown to be a great potential sorbent for Hg0 removal from coal-derived fuel gas. In this work, activated carbon (AC), Al2O3, and Beta molecular sieve were chosen as supports to disperse Pd–Fe bimetallic components. The effects of the supports on Hg0 removal of Pd–Fe bimetallic sorbents were evaluated using a fixed-bed reactor at 200 °C. The regeneration performance of sorbents was also investigated. The results showed that Hg0 removal activity and regeneration performance over Pd–Fe/AC was the best, followed by Pd–Fe/Beta, and Pd–Fe/Al2O3. The Hg0 removal efficiency of Pd–Fe/AC bimetallic sorbents remained above 80% within 400 min after regeneration 4 times. The Pd–Fe bimetallic sorbents were characterized by N2 adsorption–desorption, Fourier transform infrared spectroscopy, X-ray diffraction, CO pulse adsorption, Hg temperature-programmed thermal desorption, and X-ray photoelectron spectroscopy. The analysis results revealed that three sorbents had a similar Hg0 removal mechanism. Hg0 transformed to Pd–Hg amalgam and HgS after reacting with the sorbents. Pd0 and Fe2O3 were the active species for the removal of Hg0. The removal performance of Hg0 by Pd–Fe/Al2O3 sorbents was the lowest. It is because Pd–Fe/Al2O3 sorbents have the lowest specific surface area, surface content, and dispersion degree of the Pd component. Furthermore, Pd0 over Pd–Fe/Al2O3 sorbents was severely poisoned and transformed to PdS during the regeneration process.

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Elemental mercury removal from syngas by nano-ZnO sorbent

Cited by 19 publications

References 8 publications

Effect of the Mechanism of H₂S on Elemental Mercury Removal Using the MnO₂ Sorbent during Coal Gasification

Effect of the Mechanism of H₂S on Elemental Mercury Removal Using the MnO₂ Sorbent during Coal Gasification

Enhancement of Mercury Sorbent Using Metal Aluminate Carbonates with Chloride under Hydrothermal Conditions

Effects of Supports on Pd–Fe Bimetallic Sorbents for Hg⁰ Removal Activity and Regeneration Performance from Coal-Derived Fuel Gas

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Elemental mercury removal from syngas by nano-ZnO sorbent

Cited by 19 publications

References 8 publications

Effect of the Mechanism of H2S on Elemental Mercury Removal Using the MnO2 Sorbent during Coal Gasification

Effect of the Mechanism of H2S on Elemental Mercury Removal Using the MnO2 Sorbent during Coal Gasification

Enhancement of Mercury Sorbent Using Metal Aluminate Carbonates with Chloride under Hydrothermal Conditions

Effects of Supports on Pd–Fe Bimetallic Sorbents for Hg0 Removal Activity and Regeneration Performance from Coal-Derived Fuel Gas

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Effect of the Mechanism of H₂S on Elemental Mercury Removal Using the MnO₂ Sorbent during Coal Gasification

Effect of the Mechanism of H₂S on Elemental Mercury Removal Using the MnO₂ Sorbent during Coal Gasification

Effects of Supports on Pd–Fe Bimetallic Sorbents for Hg⁰ Removal Activity and Regeneration Performance from Coal-Derived Fuel Gas