Active manganese oxide on MnO x –CeO 2 catalysts for low-temperature NO oxidation: Characterization and kinetics study

Meng, Lingkun; Wang, Jun; Sun, Zhihui; Zhu, Jinxin; Li, Hang; Wang, Jianqiang; Shen, Meiqing

doi:10.1016/j.jre.2017.05.017

Cited by 30 publications

(16 citation statements)

References 39 publications

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“…The distribution proportions of the Mn species are listed in Table S2; the 400-12(Mn–Ce)/QS shows a higher ratio of Mn 4+ than 400-Mn/QS. That is, the coloading of Mn and Ce facilitates the formation of high valence states of manganese oxide, which has been proven to be more active in NO oxidation . As for Ce 3d XPS spectra in Figure c, 400-12(Mn–Ce)/QS shows six characteristic peaks named v, v″, v‴, u, u″, and u‴ for Ce 4+ with two additional peaks v′ and u′ related to Ce 3+ .…”

Section: Resultsmentioning

confidence: 94%

“…That is, the coloading of Mn and Ce facilitates the formation of high valence states of manganese oxide, which has been proven to be more active in NO oxidation. 30 As for Ce 3d XPS spectra in Figure 3c, 400-12(Mn−Ce)/QS shows six characteristic peaks named v, v″, v‴, u, u″, and u‴ for Ce 4+ with two additional peaks v′ and u′ related to Ce 3+ . 27 The massive number of surface Ce 4+ species is attributed to the amount of the electron transfer from Ce 3+ to Mn and O species to maintain the total charge as neutral.…”

Section: Methodsmentioning

confidence: 90%

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Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnO_x–CeO₂/Carbon Aerogels

Cheng

Xiao

Yin

et al. 2021

Ind. Eng. Chem. Res.

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Ammonia selective catalytic reduction (NH 3 -SCR), the most applied technology for abating emissions of NO x , frequently suffers from serious leakage of NH 3 and high operating temperatures. In order to overcome these limitations, melamine impregnated MnO x −CeO 2 /carbon aerogels were synthesized by the incipient wetness impregnation method for low-temperature NH 3 -free SCR of NO. The combination of carbon aerogels with highly interconnected mesoporous structures and uniform dispersed MnO x −CeO 2 can not only promote the chemisorption of nitrogen oxides but also increase the amounts of active metal sites and surface chemisorbed oxygen. Moreover, the impregnated melamine as reductant instead of NH 3 is effective to eliminate NO, avoiding the secondary pollution derived from the escape of NH 3 . Therefore, the catalyst 400-12(Mn−Ce)/QS-15mel exhibits outstanding activity with 100% steady state NO x conversion for 7 h at 185 °C. Mechanism analysis indicates that melamine-SCR is accompanied by the variation of −NH 2 and the generation of adsorbed HNCO, which could further participate in the reduction of NO without any byproducts. This work gives an in-depth understanding of the reactivity and mechanism of melamine-SCR and offers a novel route for the design of highly efficient catalysts.

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Section: Resultsmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 90%

Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnO_x–CeO₂/Carbon Aerogels

Cheng

Xiao

Yin

et al. 2021

Ind. Eng. Chem. Res.

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“…The catalyst morphology was similar to that in previous studies, 40 the active components are evenly loaded on the surface of the activated carbon with particle structure. Elemental distributions indicated well-dispersed manganese and cerium on the NAC surface and without agglomeration, 47 which helps to improve the catalytic efficiency of the catalyst.…”

Section: Results and Discussionmentioning

confidence: 99%

Stability Mechanism of Low Temperature C₂H₄–SCR with Activated-Carbon-Supported MnO_x-Based Catalyst

Liu

Zhao

et al. 2022

ACS Omega

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Manganese-based catalysts have shown great potential for use as a hydrocarbon reductant for NO x reduction (HC-SCR) at low temperatures if their catalytic stability could be further maintained. The effect of CeO 2 as a promoter and catalyst stability agent for activated carbon supported MnO x was investigated during low temperature deNO x based on a C 2 H 4 reductant. The modern characterization technology could provide a clear understanding of the activity observed during the deNO x tests. When reaction temperatures were greater than 180 °C and with ceria concentrations more than 5%, the overall NO conversion became stable near 70% during long duration testing. In situ DRIFTS shows that C 2 H 4 is adsorbed on the Mn 3 Ce 3 /NAC catalysts to generate hydrocarbon activated intermediates, R-COOH, and the reaction mechanism followed the E-R mechanism. The stability and the analytical data pointed to the formation of stable oxygen vacancies within Ce 3+ /Ce 4+ redox couplets that prevented the reduction of MnO 2 to crystalline Mn 2 O 3 and promoted the chemisorption of oxygen on the surface of MnO x -CeO x structures. Based on the data, a synergetic mechanism model of the deNO x activity is proposed for the MnO x -CeO x catalysts.

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“…Like the addition of the Fe element, Ce brought a bigger improvement for catalytic activity on NO oxidation than Mn−Fe/CC did, especially for the promotion of NO oxidation at low temperature. This result is attributed to and the synergistic effect between Mn and Ce as a process of oxygen activation, and the oxygen transferred through the redox recycles of Mn 4+ /Mn 3+ and Ce 4+ /Ce 3+[29] and Ce element can generate reactive oxygen species at the interface vacancies with other metals ,,. In order to examine the effect of Ce content, Mn (0.6) Fe (0.4) Ce/CC catalysts were prepared with a similar total amount of 10 wt %.…”

Section: Results and Discussmentioning

confidence: 99%

Mn‐Fe‐Ce Coating onto Cordierite Monoliths as Structured Catalysts for NO Catalytic Oxidation

Han

Tang

et al. 2019

ChemistrySelect

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A series of Mn‐Fe−X (X=Ce, W, Cu, Co) mixed oxides doped on cordierite monoliths as structured catalysts based monolithic for NO oxidation has been investigated. The results showed that Mn−Fe‐Ce/Al2O3/CC sample exhibited the best activity, for which a maximal NO conversion (72%) could be attained at 250 °C with the GHSV of 5971 h−1. The effects of the preparation parameters including the catalyst preparation methods and the coating material on the catalytic performance for NO catalytic oxidation was also investigated. The XRD and SEM‐EDS also indicated the coating material had a significant influence on specific surface area, surface morphology, which resulted in diﬀerences in the catalytic activity of NO catalytic oxidation. The NO+O2‐TPD results indicated that different general procedures to prepare Mn−Fe‐Ce based monolithic catalysts had a great influence on the catalytic oxidation activity of NO and Mn−Fe‐Ce/Al2O3/CC catalyst was beneficial to NO adsorption and NO2 desorption, which increased activity of catalytic oxidation of NO. The physisorption of N2 revealed that the catalyst synthesized with Al2O3 presented a higher BET specific surface area, more abundant pore structure, and better dispersion of catalysts’ active components which were favorable for catalytic oxidation reaction of NO.

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Active manganese oxide on MnO x –CeO 2 catalysts for low-temperature NO oxidation: Characterization and kinetics study

Cited by 30 publications

References 39 publications

Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnO_x–CeO₂/Carbon Aerogels

Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnO_x–CeO₂/Carbon Aerogels

Stability Mechanism of Low Temperature C₂H₄–SCR with Activated-Carbon-Supported MnO_x-Based Catalyst

Mn‐Fe‐Ce Coating onto Cordierite Monoliths as Structured Catalysts for NO Catalytic Oxidation

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Active manganese oxide on MnO x –CeO 2 catalysts for low-temperature NO oxidation: Characterization and kinetics study

Cited by 30 publications

References 39 publications

Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnOx–CeO2/Carbon Aerogels

Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnOx–CeO2/Carbon Aerogels

Stability Mechanism of Low Temperature C2H4–SCR with Activated-Carbon-Supported MnOx-Based Catalyst

Mn‐Fe‐Ce Coating onto Cordierite Monoliths as Structured Catalysts for NO Catalytic Oxidation

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Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnO_x–CeO₂/Carbon Aerogels

Ammonia-Free Selective Catalytic Reduction of NO at Low Temperature on Melamine Impregnated MnO_x–CeO₂/Carbon Aerogels

Stability Mechanism of Low Temperature C₂H₄–SCR with Activated-Carbon-Supported MnO_x-Based Catalyst