Selective catalytic reduction of NO with NH3 over MnOx-CeO2 catalysts: The great synergy between CeO2 and crystalline phase of Mn3O4

Cheng, Lijun; Sin, Songil; Ji, Jiawei; Yang, Shan; Tan, Chong; Gu, Zhiwen; Wang, Song; Huang, Chunkai; Sun, Chuanzhi; Tang, Changjin; Lin, Dong

doi:10.1016/j.fuel.2023.127772

Cited by 22 publications

(4 citation statements)

References 49 publications

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“…In a previous report, Mn-CeO 2 prepared by the impregnation method showed a higher NH 3 -desorption amount per specific surface area than Mn-CeO 2 prepared by the coprecipitation method. 46 The same phenomenon, i.e., the formation of NH 3 -adsorption sites on extralattice Mn species with Mn 3+ as the main oxidation state, namely, at the Mn content of 2 wt % or higher, might be the reason for the trend observed in this study. In fact, the NH 3 -desorption amount per specific surface area of Mn-1.0/CeO 2 (HS,Imp) was three times higher than that of CeO 2 (HS), suggesting that the Mn species with Mn 3+ as the main oxidation state present on the surface of CeO 2 increased the density of acid sites (entry 2, Table 2).…”

Section: Insight Into the Improvement Of Catalystsupporting

confidence: 67%

“…The desorbed amount of NH 3 per specific surface area was almost halved by introducing Mn species at 0.5–2.0 wt % (entries 2–5) and then increased with the increase in the Mn content (entries 7 and 8). In a previous report, Mn-CeO 2 prepared by the impregnation method showed a higher NH 3 -desorption amount per specific surface area than Mn-CeO 2 prepared by the coprecipitation method . The same phenomenon, i.e.…”

Section: Resultsmentioning

confidence: 99%

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Improvement of Stability of CeO₂–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Fujii

Yabushita

et al. 2023

ACS Catal.

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Cerium oxide (CeO2) was recently reported to function as a highly active heterogeneous catalyst in the flow synthesis of 2-imidazolidinone (EU) without gas-phase CO2 from ethylenediamine carbamate (EDA-CA), the latter of which can be synthesized easily from ethylenediamine (EDA) and ambient CO2, in an EDA solvent. However, catalyst deactivation due to the surface deposition of polyurea-like compounds has remained a grand challenge. In this study, in an attempt to develop new catalysts with better stability than conventional CeO2 by tuning surface properties, the addition of a second metal to CeO2 was examined in the kinetic region. Mn-doped CeO2 (Mn content = 1 wt %) prepared via a coprecipitation method was found to be a more stable catalyst in the EU production with a lower deactivation rate constant of 0.018 h–1 than the pure CeO2 (0.058 h–1). Mn species incorporated in the CeO2 lattice exhibited good resistance against their leaching during the reactions operated in the EDA solvent, leading to a higher stability of Mn-doped CeO2 catalysts than the pure CeO2 and also Mn-loaded CeO2 that readily underwent the leaching of Mn species during the reaction. The origin of the better stability of Mn-doped CeO2 than pure CeO2 was suggested from various characterization data to be the decreased density of the acid sites. The high density of acid sites of the pure CeO2 possibly leads to the multipoint adsorption of polyurea-like compounds, resulting in the catalyst deactivation. In contrast, the low density of acid sites has been suggested to retard such undesirable interactions with catalyst poisons and thus improved the catalyst stability in the EU production from EDA-CA in the EDA solvent.

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Section: Insight Into the Improvement Of Catalystsupporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Improvement of Stability of CeO₂–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Fujii

Yabushita

et al. 2023

ACS Catal.

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“…In contrast, the NO reaction order for the UT-Fe 2 O 3 catalyst changed to 0.85, implying the simultaneous involvement of L–H and E–R mechanisms in contributing to the reaction. In other words, the adsorbed NO x species actually participate in the reaction together with gaseous NO. , …”

Section: Resultsmentioning

confidence: 99%

“…In other words, the adsorbed NO x species actually participate in the reaction together with gaseous NO. 54,55 Based on the above results, a possible reaction mechanism of ultrasonic treatment on improving NH 3 −SCR performance is proposed and schematically illustrated in Figure 7. Due to the enhanced diffusion of lattice oxygen induced by creation of a bulk defect, the process of NO oxidation is facilitated.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Lattice Oxygen Activation Triggered by Ultrasonic Shock Significantly Improves NO Selective Catalytic Reduction

Wang,

Zhu,

Sin

et al. 2024

ACS Catal.

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The precise regulation of lattice oxygen is crucial for many redox reactions, but it still remains a formidable challenge. Herein, we reported a facile strategy to induce generation of bulk phase defects in hematite (α-Fe 2 O 3 ) by ultrasonic treatment, thus achieving exclusive lattice oxygen activation without additional alternation of surface adsorbed oxygen species. This kind of unique lattice oxygen activation afforded negligible disturbance of NH 3 adsorption but significant influence on NO 2 generation via accelerated oxygen diffusion, resulting in enhanced activity contribution from the Fast-SCR reaction pathway. Particularly, the generation of bulk-phase defects was also found to be conducive to create thermally instable and chemically reactive surface nitrate species, which played a decisive role in activating NO reactant. Accordingly, a triple increment in the deNO x performance of the α-Fe 2 O 3 catalyst for the reaction of selective catalytic reduction of NO with NH 3 (NH 3 −SCR) was achieved.

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Promoting the NH3-SCR performance of Fe2O3-TiO2 catalyst through regulation of the exposed crystal facets of Fe2O3

Teng,

Li,

Dai

et al. 2024

Applied Surface Science

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Selective catalytic reduction of NO with NH3 over MnOx-CeO2 catalysts: The great synergy between CeO2 and crystalline phase of Mn3O4

Cited by 22 publications

References 49 publications

Improvement of Stability of CeO₂–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Improvement of Stability of CeO₂–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Lattice Oxygen Activation Triggered by Ultrasonic Shock Significantly Improves NO Selective Catalytic Reduction

Promoting the NH3-SCR performance of Fe2O3-TiO2 catalyst through regulation of the exposed crystal facets of Fe2O3

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Selective catalytic reduction of NO with NH3 over MnOx-CeO2 catalysts: The great synergy between CeO2 and crystalline phase of Mn3O4

Cited by 22 publications

References 49 publications

Improvement of Stability of CeO2–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Improvement of Stability of CeO2–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Lattice Oxygen Activation Triggered by Ultrasonic Shock Significantly Improves NO Selective Catalytic Reduction

Promoting the NH3-SCR performance of Fe2O3-TiO2 catalyst through regulation of the exposed crystal facets of Fe2O3

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Product

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Improvement of Stability of CeO₂–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate

Improvement of Stability of CeO₂–Based Catalysts by Mn Doping for the Synthesis of 2-Imidazolidinone from Ethylenediamine Carbamate