Regenerable CoxMn3−xO4 spinel sorbents for elemental mercury removal from syngas: Experimental and DFT studies

Wang, Zhen; Liu, Jing; Yang, Yingju; Yu, Yingni; Yan, Xuchen; Zhang, Zhen

doi:10.1016/j.fuel.2020.117105

Cited by 33 publications

(23 citation statements)

References 47 publications

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“…As shown in Figure 2, the XRD pattern of the prepared single manganese oxide in the presence of VC (Mn 2 O 3 − 0.3VC, Figure 2a) revealed characteristic Mn 2 O 3 diffractions 44,48 Especially, on increasing the calcination temperature to 500 °C, the crystallinity of the Mn 3 Co 2 O x − 0.3VC-500 catalyst (Figure 2c) was significantly enhanced and obvious diffraction peaks belonging to the Mn−Co spinel structure (JCPDS#18-0408) could be observed. The Mn−Co oxides prepared with different VC contents (Figure 2d, 0− 0.4VC) revealed a similar crystalline structure to that of the Mn 3 Co 2 O x −0.3VC catalyst.…”

Section: Resultsmentioning

confidence: 97%

“…According to the X-ray diffraction (XRD) results and previous works (Figure ), a Mn–Co tetragonal crystal structure (Mn 2 CoO 4 , mp-1221996) was selected from the Materials Project as the calculation model to simulate the Mn–Co spinel oxides in this study. − To ensure the rationality of the calculation results, the XRD pattern of the selected model was calculated. It has been found that the simulated XRD pattern of the Mn–Co model was well consistent with the Mn 3 Co 2 O x –0.3VC-500 catalyst (Figure S1), demonstrating that the calculations are faithworthy.…”

Section: Methodsmentioning

confidence: 99%

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Vitamin C-Assisted Synthesized Mn–Co Oxides with Improved Oxygen Vacancy Concentration: Boosting Lattice Oxygen Activity for the Air-Oxidation of 5-(Hydroxymethyl)furfural

et al. 2021

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The catalytic oxidation of biomass-derived 5-(hydroxymethyl)furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising route to produce bioplastic monomers. Developing budget non-noble-metal catalysts for the efficient air-oxidation of HMF to FDCA is highly demanded but challenging. In this contribution, we present a facile and green vitamin C (VC)-assisted solid-state grinding method for synthesizing mesoporous Mn–Co spinel oxides with improved oxygen vacancy (Ov) concentration, which could offer a satisfactory FDCA yield of 96% using air as the oxygen source (130 °C, 1.5 MPa air, 3 h). Remarkably, Mn3Co2O x –0.3VC offered an outstanding FDCA formation rate of 2611 μmolFDCA·gcat –1·h–1, which is the highest value achieved so far among ever-described Mn-based catalysts. Based on experimental studies, the catalytic performance of Mn–Co oxides for the oxidation of HMF corresponds well with their Mn–O bond intensities. The catalyst with a higher Ov concentration exhibits a weaker Mn–O bond intensity, which brings about a higher lattice oxygen (OL) reactivity. More importantly, density functional theory (DFT) calculations also demonstrate that increasing the Ov amount not only boosts the OL reactivity of the catalyst by reducing the formation energy of Ov but also contributes to the adsorption and activation of O2 over the catalyst by significantly cutting down the O2 adsorption energy, thus leading to an enhanced catalytic activity for the oxidation of HMF. Besides, the catalyst with a higher Ov concentration provides a stronger substrate adsorption ability, which may also promote the HMF oxidation reactions. This work provides insights into the role of Ov over Mn-based oxides in oxidation catalysis by a Mars–van Krevelen mechanism.

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Vitamin C-Assisted Synthesized Mn–Co Oxides with Improved Oxygen Vacancy Concentration: Boosting Lattice Oxygen Activity for the Air-Oxidation of 5-(Hydroxymethyl)furfural

et al. 2021

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“…The excellent catalytic activity of copper-manganese oxide is closely related to the flexible valence states of Cu +/2+ and Mn 2+/3+/4+ [33]. The valence state changes of copper and manganese cations easily lead to an electron-transfer environment [34], which is beneficial to the adsorption and oxidation of Hg 0 . Therefore, our previous work synthesized copper-manganese spinel-type oxide and used to remove Hg 0 from simulated flue gas (4% O 2 + 12% CO 2 + N 2 ) [35][36][37].…”

Section: Introductionmentioning

confidence: 99%

HCl-Induced Hg0 Transformation over CuMn2O4 Sorbent

Zhang¹,

Yang²,

Jing³

et al. 2022

Energy Engineering

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CuMn 2 O 4 spinel has been regarded as a highly efficient sorbent for Hg 0 capture from flue gas. The regenerability and recyclability of CuMn 2 O 4 sorbent are mainly associated with the mercury speciation adsorbed on its surface. However, the effect mechanism of HCl on Hg 0 transformation over CuMn 2 O 4 sorbent is still elusive. Experiments were conducted to understand the effect of HCl on Hg 0 transformation over CuMn 2 O 4 sorbent. The results indicate that CuMn 2 O 4 sorbent is a mesoporous material and possesses a good thermal stability. CuMn 2 O 4 shows >95% Hg 0 removal efficiency in a wide temperature window of 50-350 • C. The favorable electron-transfer environment caused by the mixed valence states of Cu and Mn cations is responsible for the excellent Hg 0 removal performance of CuMn 2 O 4 sorbent. CuMn 2 O 4 shows a higher Hg 0 adsorption capacity of 4774.57 μg/g. Hg 0 adsorption process over CuMn 2 O 4 sorbent can be well described by the developed kinetic model. Hg 0 removal efficiency of CuMn 2 O 4 sorbent does not depend on the presence of HCl. Mercury species adsorbed on the CuMn 2 O 4 sorbent in the presence of HCl mainly exist in the forms of HgO and HgCl 2 O 8 • H 2 O. HCl shows a significant effect on mercury speciation over CuMn 2 O 4 sorbent. Most of HgO species will be transformed into HgCl 2 O 8 • H 2 O in the presence of HCl.

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“…34 As shown in Figure 2, Hg 0 adsorbent injection is an effective technology for Hg 0 removal. 40,41 Hg 0 adsorbent is usually injected between the downstream of the air preheater (APH) and the upstream of particulate control device such as ESP or FF. 42 Among various Hg 0 adsorbents, activated carbon is one of the most universal Hg 0 adsorbents.…”

Section: Introductionmentioning

confidence: 99%

“…As shown in Figure , Hg 0 adsorbent injection is an effective technology for Hg 0 removal. , Hg 0 adsorbent is usually injected between the downstream of the air preheater (APH) and the upstream of particulate control device such as ESP or FF . Among various Hg 0 adsorbents, activated carbon is one of the most universal Hg 0 adsorbents. − However, as activated carbon has the disadvantage of high cost, − it is necessary to find other moderate adsorbents which can replace activated carbon for Hg 0 removal effectively and economically. − Among other moderate Hg 0 adsorbents, fly ash obtained from coal-fired power plant (CFPP) can be used as a promising substitute for activated carbon for Hg 0 removal with the advantages of low cost, abundance, and easy access .…”

Section: Introductionmentioning

confidence: 99%

Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

Liu

Zhao

et al. 2020

Energy Fuels

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Mercury (Hg), in particular elemental mercury (Hg0) captured from coal-fired power plants, has attracted much attention because of its severe harm to human health and environment. Hg0 can be removed using the technology of adsorbent injection, and one of the promising adsorbents is fly ash. To evaluate the effect of complex multifactors of fly ash on Hg0 removal performance, this review summarizes, analyzes, and evaluates the quantitative effects of fly ash compositions, physical parameters, flue gas components, and modification reagents. The effects of electric field (EF), magnetic field (MF), and ultraviolet (UV) light on Hg0 removal using fly ash are also introduced. Unburned carbon (UBC) and Fe2O3 are two reactive components in fly ash for Hg0 oxidation. Physical parameters including higher specific surface area, larger total pore volume, and wider distribution of pores with well-developed micropores are beneficial for Hg0 retention, and no consistent relationship between particle size and Hg0 retention using fly ash has been obtained. While gas phase components including HCl, NO, and O2 promote the removal of Hg0 using fly ash, no agreement about the effects of SO2 and H2O vapor on Hg0 removal has been reached. The promotion of halogen-modified fly ash on Hg0 removal may be explained by the Langmuir–Hinshelwood mechanism, the Mars–Maessen mechanism, as well as the Eley–Ridel mechanism. The contribution of metal-modified fly ash to Hg0 removal is attributed to the oxidation ability of metal oxides as well as metal positive ions. EF, MF, and UV light enhance the oxidation of Hg0 using fly ash to different degrees. The promotion of EF may be attributed to the formation of more Cl, O, and OH radicals by a series of electron-induced reactions. The enhancement of MF is simultaneously attributed to the energy-level splitting of Hg0 as well as the magnetochemistry effect of magnetic materials in fly ash. The function of fly ash on the photocatalytic oxidation of Hg0 under the UV light has been verified, while relevant studies are still limited. More studies are still needed on the relationship between surface functional groups and carbon types, the control of Hg0 secondary emission from the spent fly ash, the development of fly ash-based products, the compromise between fly ash modification cost and Hg0 removal efficiency, and the effective and economical coremoval of Hg0, NO x , and SO x using fly ash. In particular, the promotional effects of EF, MF, and UV light on Hg0 removal necessitate extensive studies on their underlining mechanisms. This review resolves the existing controversies on the Hg0 removal mechanism and promotes the development of fly ash on Hg0 removal from coal combustion.

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Regenerable CoxMn3−xO4 spinel sorbents for elemental mercury removal from syngas: Experimental and DFT studies

Cited by 33 publications

References 47 publications

Vitamin C-Assisted Synthesized Mn–Co Oxides with Improved Oxygen Vacancy Concentration: Boosting Lattice Oxygen Activity for the Air-Oxidation of 5-(Hydroxymethyl)furfural

Vitamin C-Assisted Synthesized Mn–Co Oxides with Improved Oxygen Vacancy Concentration: Boosting Lattice Oxygen Activity for the Air-Oxidation of 5-(Hydroxymethyl)furfural

HCl-Induced Hg0 Transformation over CuMn2O4 Sorbent

Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

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