Hollow MnOx-CeO 2 mixed oxides as highly efficient catalysts in NO oxidation

Shen, Qun; Zhang, Lingyun; Sun, Nannan; Wang, Hui; Zhong, Liangshu; He, Chi; Wei, Wei; Sun, Yuhan

doi:10.1016/j.cej.2017.02.148

Cited by 155 publications

(53 citation statements)

References 40 publications

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“…[19][20][21][22][23] Therefore, it can be imagined that modifying MnO 2 nanomaterials with CeO 2-δ could be an effective strategy to enhance the oxygen transferring by utilizing CeO 2-δ as a possible mediator. [18,24,25] Even though the enhanced catalytic performance in CO, C 3 H 8 , NO, Hg 0 and soot oxidation on Ce-Mn mixed oxides has been contributed to the synergistic effect between Ce and Mn, [24,[26][27][28][29][30] the exact mechanism of synergistic effect between CeO 2-δ and MnO 2 , as well as the relationship with surrounding atmospheres is still not clear enough, and needs further exploring.…”

Section: Introductionmentioning

confidence: 99%

Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

Huang

Zhao

Chang

et al. 2018

Applied Surface Science

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In this research, β-MnO 2 nanorods were synthesized by a hydrothermal method, followed by a facile precipitation method to obtain nanocrystalline CeO 2-δ coated β-MnO 2 nanorods. The as-prepared samples were characterized by XRD, HRTEM, FESEM, XPS and in-situ high-temperature XRD. The HRTEM results show that well dispersed CeO 2-δ nanocrystals sized about 5 nm were coated on the surface of β-MnO 2 nanorods. The oxygen storage and transfer property of as-synthesized materials were evaluated using TGA under various atmospheres (air, pure N 2 , and 5%H 2 /95%Ar). The TGA results indicate that CeO 2-δ modification could favour the reduction of Mn 4+ to Mn 3+ and/or Mn 2+ at lower temperature as compared with pure β-MnO 2 nanorods and the physically mixed CeO 2-δ-β-MnO 2 under low oxygen partial pressure conditions (i.e., pure N 2 , 5%H 2 /95%Ar). Specifically, CeO 2-δ @β-MnO 2 sample can exhibit 7.5 wt% weight loss between 100 and 400 o C under flowing N 2 and 11.4 wt% weight loss between 100 and 350 o C under flowing 5%H 2 /95%Ar. During the reduction process under pure N 2 or 5%H 2 /95%Ar condition, the oxygen ions in β-MnO 2 nanorods are expected to be released to the surroundings in the form of O 2 or H 2 O with the coated CeO 2-δ nanocrystals acting as mediator as inferred from the synergistic effect between the well-interacted CeO 2-δ nanocrystals and β-MnO 2 nanorods.

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Section: Introductionmentioning

confidence: 99%

Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

Huang

Zhao

Chang

et al. 2018

Applied Surface Science

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“…As for the low-temperature activity, Liu et al created a novel SCR catalyst with MnO x -CeO 2 supported on Cu-SSZ-13 which reached an NO conversion efficiency of over 90% at 150 • C. Furthermore, they found that adding MnO x -CeO 2 facilitated the conversion of bridging nitrate to monodentate nitrate, which might be the reason for the improved activity [24]. Meanwhile, considerable Mn-based and Ce-based oxide catalysts were investigated due to their excellent low-temperature SCR activities [25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Co-Exchange of Mn: A Simple Method to Improve Both the Hydrothermal Stability and Activity of Cu–SSZ-13 NH3–SCR Catalysts

Zhang

et al. 2019

Catalysts

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A series of Cu–Mn–SSZ-13 catalysts were obtained by co-exchange of Mn and Cu into SSZ-13 together (ion exchange under a mixed solution of Cu(NO3)2 and Mn(NO3)2) and compared with Cu–SSZ-13 catalysts on the selective catalytic reduction (SCR) of nitric oxide (NO) by ammonia. The effects of total ion exchange degree and the effect of Mn species on the structure and performance of catalysts before and after hydrothermal aging were studied. All fresh and aged catalysts were characterized with several methods including temperature-programmed desorption with NH3 (NH3-TPD), X-ray diffraction (XRD), 27Al and 29Si solid-state nuclear magnetic resonance (NMR), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and low-temperature N2 adsorption–desorption techniques. The results showed that the increase of the total ion exchange degree can reduce the content of residual Brønsted acid sites of catalysts, thus relieved the dealumination and the decrease of crystallinity of the catalyst during hydrothermal aging. The moderate addition of a Mn component in Cu–Mn–SSZ-13 catalysts significantly increased the activity of NO conversion at low temperature range. The selected Cu(0.2)Mn(0.1)–SSZ-13 catalyst achieved a high NO conversion of >90% in the wide and low temperature range of 175–525 °C and also exhibited good N2 selectivity and excellent hydrothermal stability, which was related to the inhibition of the Mn component on the aggregation of Cu species and the pore destruction of the catalyst during hydrothermal aging.

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“…including both metal oxides, noble metals, zeolites and carbon materials. Carbon materials and zeolites always exhibit high oxidation activity at room temperature, However, in the real conditions of industrial application, the catalysts with qualified catalytic performance at middle temperature (150‐300 °C) is much better . Noble metals like Pt‐based catalysts have excellent catalytic oxidation activity, but it is obvious that the high cost of Pt limits its application.…”

Section: Introductionmentioning

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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Hollow MnOx-CeO 2 mixed oxides as highly efficient catalysts in NO oxidation

Cited by 155 publications

References 40 publications

Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

Nanocrystalline CeO2−δ coated β-MnO2 nanorods with enhanced oxygen transfer property

Co-Exchange of Mn: A Simple Method to Improve Both the Hydrothermal Stability and Activity of Cu–SSZ-13 NH3–SCR Catalysts

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

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