Promoting Diesel Soot Combustion Efficiency over Hierarchical Brushlike α-MnO2 and Co3O4 Nanoarrays by Improving Reaction Sites

Li, Geng; Yu, Jiahuan; Chen, Li; Feng, Nengjie; Meng, Jie; Fan, Fang; Zhao, Peng; Wang, Lei; Wan, Hui; Guan, Guofeng

doi:10.1021/acs.iecr.9b02155

Cited by 25 publications

(11 citation statements)

References 88 publications

(248 reference statements)

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“…The soot ignition temperature was lower than the values for the other catalysts analyzed and, together with an estimated T 90 value of 923 K, indicated the higher activity of this material in the soot removal process. Although the values are slightly higher than those registered for new materials for diesel particulate filters, such as hierarchical brushlike α-MnO 2 and Co 3 O 4 nanoarrays, 65 or CeO 2 modified with Fe, Ba or Cu, 58,66 where the incorporation of metals generated oxygen vacancies in the catalyst, the elimination of soot under oxidant atmosphere was carried out at lower temperatures and higher rate than DeNOx catalyst, acting as an effective passive converter.…”

Section: Methodsmentioning

confidence: 77%

Understanding of Soot Removal Mechanism over DeNOx-Catalysts as Passive Converters

Cortés‐Reyes

Herrera

Larrubia

et al. 2021

Ind. Eng. Chem. Res.

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Although diesel particulate filters (DPFs) are able to efficiently remove soot and coupled NO x storage and reduction and selective catalytic reaction (NSR−SCR) technologies can considerably decrease NO x emissions, the elimination of soot over Pt−Ba− K/Al 2 O 3 and Cu-CHA NO x removal catalysts acting as passive converters is still an open topic. The estimation of the occurrence frequency and activation energy values from the distribution function of activation energy allowed the identification of sequential steps involved in the soot removal. For that, TG-MS nonisothermal experiments were carried out over the model of deNO x catalysts under a NO+O 2 atmosphere. For bare soot, only gas-phase components react with carbon particles to produce CO 2 at high temperatures with E a values higher than 120 kJ mol −1 for the direct oxidation by molecular oxygen and 114 kJ mol −1 for the assisted soot removal process by NO x . For the lean NO x trap (LNT) model catalyst, the combination of hydroxylated centers, provided by the incorporation of potassium responsible for the carbon elimination via gasification (70−90 kJ mol −1 ), and nitrate species stored onto the surface, involved in the elimination via oxidation (97 kJ mol −1 ), together with the gas-phase interaction, makes this catalyst an efficient soot passive converter. The Cu-SAPO-34 SCR catalyst with 4 wt % of copper located inside the framework and small pores of the chabazite structure are not able to act as a converter because soot removal takes place via assisted combustion with NO x and molecular oxygen, similar to the uncatalyzed process. CeO 2 , the main component of DPF, presented the lowest values of T 90 (923 K), ignition soot temperature, and activation energy due to the intervention of highly reactive oxygen species being the most effective soot converter in the low-temperature range.

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Section: Methodsmentioning

confidence: 77%

Understanding of Soot Removal Mechanism over DeNOx-Catalysts as Passive Converters

Cortés‐Reyes

Herrera

Larrubia

et al. 2021

Ind. Eng. Chem. Res.

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“…Raman spectroscopy was carried out to obtain better confirmation of the structural characteristics of the as-prepared catalysts. Generally, a weaker Mn–O bond leads to a higher reactivity. , The Raman spectra of NF, NF&NW, NW, and Ag(10)-NF are shown in Figure . The peak around 630.9–639.6 cm –1 belongs to the symmetric stretching vibrations (ν(Mn–O)) perpendicular to the direction of the [MnO 6 ] octahedral double chains .…”

Section: Resultsmentioning

confidence: 99%

Promoting the Generation of Active Oxygen over Ag-Modified Nanoflower-like α-MnO₂ for Soot Oxidation: Experimental and DFT Studies

Wang

Zhang

et al. 2020

Ind. Eng. Chem. Res.

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The hydrothermal method was used to synthesize α-MnO 2 with nanoflower-like (NF) and nanowire-like (NW) morphologies. Besides, different amounts (5−15 wt %) of silver were loaded into flowerlike α-MnO 2 (Ag(x)-NF) to promote the soot oxidation performance. The resulting catalysts have been characterized by different techniques. Soot oxidation was detected over temperature-programmed experiments. Unequal surface oxygen vacancies in different α-MnO 2 result in different O x n− generating capacities, as shown in the X-ray photoelectron spectroscopy (XPS) test. The NF had the highest ratio of highly reactive superoxide (O 2 − ). In addition, the NF modified by optimal amounts of Ag could speed up the O 2 − generation caused by the largest amount of surface oxygen vacancies. The density functional theory calculation revealed that the oxygen vacancies on α-MnO 2 species could improve the adsorption of reactants and increase the surface energy of the asprepared catalyst, which result in excellent catalytic performance of Ag(10)-NF.

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“…[ 92,211,535–538 ] Ultrathin MnO 2 nanosheet array, [ 537 ] mesoporous MnO 2 , [ 539 ] Cu and Co bidoped α‐MnO 2 nanowires, [ 535 ] and Ag‐modified α‐MnO 2 nanoflowers [ 300 ] have been studied by researchers and have proven to be an ideal material for efficient soot removal. In addition, MnO 2 coatings (such as δ‐MnO 2 coating on 3D nickel foam [ 92 ] and α‐MnO 2 coating on Fe 75 Ni 25 novel 3D‐structured foam [ 536 ] ), MnO 2 based nanocomposites (such as trepang‐like CeO 2 @MnO 2 , [ 211 ] hierarchical brushlike α‐MnO 2 and Co 3 O 4 nanoarrays, [ 540 ] MnO 2 /wire‐mesh monoliths, [ 541 ] CeO 2 –MnO 2 /Al 2 O 3 , [ 542 ] and MnO 2 /CuO‐porous zeolite beta [ 543 ] ) have also exhibited strong soot removal performances.…”

Section: Environmental Applicationsmentioning

confidence: 99%

MnO₂‐Based Materials for Environmental Applications

et al. 2021

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Manganese dioxide (MnO2) is a promising photo–thermo–electric‐responsive semiconductor material for environmental applications, owing to its various favorable properties. However, the unsatisfactory environmental purification efficiency of this material has limited its further applications. Fortunately, in the last few years, significant efforts have been undertaken for improving the environmental purification efficiency of this material and understanding its underlying mechanism. Here, the aim is to summarize the recent experimental and computational research progress in the modification of MnO2 single species by morphology control, structure construction, facet engineering, and element doping. Moreover, the design and fabrication of MnO2‐based composites via the construction of homojunctions and MnO2/semiconductor/conductor binary/ternary heterojunctions is discussed. Their applications in environmental purification systems, either as an adsorbent material for removing heavy metals, dyes, and microwave (MW) pollution, or as a thermal catalyst, photocatalyst, and electrocatalyst for the degradation of pollutants (water and gas, organic and inorganic) are also highlighted. Finally, the research gaps are summarized and a perspective on the challenges and the direction of future research in nanostructured MnO2‐based materials in the field of environmental applications is presented. Therefore, basic guidance for rational design and fabrication of high‐efficiency MnO2‐based materials for comprehensive environmental applications is provided.

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Promoting Diesel Soot Combustion Efficiency over Hierarchical Brushlike α-MnO₂ and Co₃O₄ Nanoarrays by Improving Reaction Sites

Cited by 25 publications

References 88 publications

Understanding of Soot Removal Mechanism over DeNOx-Catalysts as Passive Converters

Understanding of Soot Removal Mechanism over DeNOx-Catalysts as Passive Converters

Promoting the Generation of Active Oxygen over Ag-Modified Nanoflower-like α-MnO₂ for Soot Oxidation: Experimental and DFT Studies

MnO₂‐Based Materials for Environmental Applications

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Promoting Diesel Soot Combustion Efficiency over Hierarchical Brushlike α-MnO2 and Co3O4 Nanoarrays by Improving Reaction Sites

Cited by 25 publications

References 88 publications

Understanding of Soot Removal Mechanism over DeNOx-Catalysts as Passive Converters

Understanding of Soot Removal Mechanism over DeNOx-Catalysts as Passive Converters

Promoting the Generation of Active Oxygen over Ag-Modified Nanoflower-like α-MnO2 for Soot Oxidation: Experimental and DFT Studies

MnO2‐Based Materials for Environmental Applications

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Product

Resources

About

Promoting Diesel Soot Combustion Efficiency over Hierarchical Brushlike α-MnO₂ and Co₃O₄ Nanoarrays by Improving Reaction Sites

Promoting the Generation of Active Oxygen over Ag-Modified Nanoflower-like α-MnO₂ for Soot Oxidation: Experimental and DFT Studies

MnO₂‐Based Materials for Environmental Applications