NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Wu, Xu; Liu, Lili; Liu, Jiangning; Hou, Benhui; Du, Yali; Xie, Xianmei

doi:10.1016/j.apcata.2020.117918

Cited by 17 publications

(8 citation statements)

References 58 publications

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“…DFT simulations found species such as NO 2 and NH 2 as key intermediates for NH 3 SCR. Wu et al and Zhang et al reported the formation of intermediate species such as NO 2 and NH 2 from their in situ DRIFTS analysis carried out on Ni-based catalysts and reported them as the active intermediates in NH 3 –SCR reaction, supporting our findings and confirming the validity of the proposed mechanisms. The NH 2 and NO 2 species underwent N–N coupling to form an H 2 NNO 2 intermediate ( E a = 1.18 eV and Δ E = −1.35 eV).…”

Section: Resultssupporting

confidence: 88%

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH₃

Selvaraj,

Aghalayam,

Varghese

2023

J. Phys. Chem. C

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A detailed mechanistic investigation of the selective catalytic reduction (SCR) of NO with NH 3 was carried out on NiO(100) and NiO(110) surfaces using density functional theory (DFT) simulations. On stoichiometric NiO surfaces, the high barrier for O 2 dissociation resulted in a NO-assisted O 2 dissociation to form NO 2 , NH 3 dehydrogenation by active oxygen, NO 2 −NH 2 coupling, and N 2 O formation, ultimately leading to the product N 2 via N−O bond cleavage of N 2 O. On NiO(100), the N−O bond cleavage in N 2 O, and on NiO(110), the N−N coupling had high barriers of 1.95 eV. On NiO(100), N 2 O was a likely side product aside from N 2 . On partially reduced NiO surfaces, facile direct O 2 activation at the oxygen vacancy led to a mechanistic shift to a NO-mediated pathway. This enabled selective N 2 formation on partially reduced NiO(100) and NiO(110) surfaces, with the highest activation barrier of less than 0.89 eV. Substitutional doping of NiO with Ru facilitated enhanced reducibility of the surface and strong interaction of O with the Ru site and reduced the N−O breaking barrier, enhancing the catalytic activity compared to undoped NiO. The partially reduced Ru-doped NiO surface exhibited activation barriers lower than those on the stoichiometric Ru-doped NiO surface and formed N 2 . These results indicate the possibility of enhancing catalytic activity and selectivity of NiO catalysts for lowtemperature SCR by modulating the reducibility of the surface and by substitutional doping, which enhances the Lewis acidity of the catalyst by modulating the local electronic structure around the metal sites.

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Section: Resultssupporting

confidence: 88%

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH₃

Selvaraj,

Aghalayam,

Varghese

2023

J. Phys. Chem. C

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“…Mn 2p 3/2 could be fitted into three peaks, indicating that Mn species existed in a mixed valence state of Mn 4+ (643.7 eV), Mn 3+ (641.9 eV), and Mn 2+ (640.9 eV). , The Mn 4+ /Mn 3+ ratio decreased in the following order: Ni 0.5 Mn 0.5 Fe 0.5 O x (1.45) > Ni–Mn–Fe/γ-Al 2 O 3 (1.27) > Mn/γ-Al 2 O 3 (1.08). In addition, it has been reported that the presence of other metal ions contributes to the activity of Mn-based catalysts . According to the quantitative analysis of the XPS spectra, the ratio of Fe 3+ /Fe 2+ was 1.8 and 0.98 in Ni 0.5 Mn 0.5 Fe 0.5 O x and Ni–Mn–Fe/γ-Al 2 O 3 , respectively (Figure S6c).…”

Section: Resultsmentioning

confidence: 89%

“…After the adsorption of NH 3 by the Ni 0.5 Mn 0.5 Fe 0.5 O x catalyst, the bands at ∼1701 and 1479 cm –1 could be assigned to the NH 4 + species on Brønsted acid sites, , and the bands at ∼1598 and 1180 cm –1 corresponded to the coordinated NH 3 at Lewis acid sites (Figure S7e,f). For the Mn/γ-Al 2 O 3 catalyst, the IR bands at ∼1690 and 1215 cm –1 were associated with NH 4 + and NH 3 species bound to Brønsted and Lewis acid sites, respectively. Obviously, for Ni 0.5 Mn 0.5 Fe 0.5 O x , the IR band strength of NH 3 adsorption at the Brønsted and Lewis acid sites was higher.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, it has been reported that the presence of other metal ions contributes to the activity of Mn-based catalysts. 41 According to the quantitative analysis of the XPS spectra, the ratio of Fe 3+ / Fe 2+ was 1.8 and 0.98 in Ni 0.5 Mn 0.5 Fe 0.5 O x and Ni−Mn−Fe/γ-Al 2 O 3 , respectively (Figure S6c). It has been reported that Fe 3+ ions have higher catalytic activity than Fe 2+ ions; thus, more Fe 3+ species on the catalyst surface are positive for the NH 3 − SCR reaction.…”

Section: Transient Kinetics Studiesmentioning

confidence: 95%

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Mechanistic Insight into the Promotion of the Low-Temperature NH₃–SCR Activity over NiMnFeO_x LDO Catalysts: A Combined Experimental and DFT Study

Yan,

Xiao,

Gui

et al. 2023

Environ. Sci. Technol.

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“…In addition, the other two peaks at 300-400 C attributed to the NH 4 + species on strong acidity sites. [21,22] It is generally believed that strong acid sites are crucial to promote DeNO x activity, because NH 3 coordinated by a lone pair of electrons on NH 3 is more stable than NH 4 + . [23] With the data of NH 3 -TPD in Table 4, the surface acid amount of the catalysts can be arranged in the following order: Mn 2 Ti 8 (H 2 BDC: M = 3) > Mn 3 Ti 7 (H 2 BDC:M = 3) > Mn 1 Ti 9 (H 2 BDC: M = 3) > Mn 1 Ti 9 (H 2 BDC:M = 4) > Mn 1 Ti 9 (H 2 BDC: M = 2).…”

Section: Nh 3 -Tpd Resultsmentioning

confidence: 99%

A novel MnTi mixed oxide catalyst engineered by metal–organic framework precursor for enhancing NO_x removal performance

et al. 2023

Applied Organom Chemis

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In this research, MnTi metal-organic frameworks (MnTi-MOFs) were successfully prepared, and derived catalysts were innovatively applied to the removal of NO x by selective catalytic reduction with NH 3 (NH 3 -SCR). The test results show that the one-step controllable synthesis of MnTi-MOFs material is achieved through adjusting the Mn/Ti molar ratios and the proportion of metal to organic ligands, in which the ratio of organic ligands is vitally significant for the synthesis of MnTi-MOFs (MnTi-MOFs can only be synthesized with the ligand to metal molar ratio in the range of 3-4). Owing to the special heterogeneity of MOFs, the catalyst sample derived from the MnTi-MOFs precursor prepared with suitable raw material ratio exhibits the best SCR performance. Series of characterization analyses show that the catalysts derived from MOFs precursors with ordered lattice structure exhibit an appropriate surface chemical adsorption oxygen, an increased Mn 4+ /Mn n+ content, and enhanced acidity of the surface of the sample. This research affords an innovative method to the controllable preparation of dual metal MOFs and expands the development of catalysts in the field of low-temperature de-NO x .

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NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Cited by 17 publications

References 58 publications

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH₃

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH₃

Mechanistic Insight into the Promotion of the Low-Temperature NH₃–SCR Activity over NiMnFeO_x LDO Catalysts: A Combined Experimental and DFT Study

A novel MnTi mixed oxide catalyst engineered by metal–organic framework precursor for enhancing NO_x removal performance

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NiMn mixed oxides with enhanced low-temperature deNOx performance: Insight into the coordinated decoration of MnOx by NiO phase via glycine combustion method

Cited by 17 publications

References 58 publications

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH3

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH3

Mechanistic Insight into the Promotion of the Low-Temperature NH3–SCR Activity over NiMnFeOx LDO Catalysts: A Combined Experimental and DFT Study

A novel MnTi mixed oxide catalyst engineered by metal–organic framework precursor for enhancing NOx removal performance

Contact Info

Product

Resources

About

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH₃

Influence of Oxygen Vacancy and Dopant in NiO Catalysts on the Selective Catalytic Reduction of NO with NH₃

Mechanistic Insight into the Promotion of the Low-Temperature NH₃–SCR Activity over NiMnFeO_x LDO Catalysts: A Combined Experimental and DFT Study

A novel MnTi mixed oxide catalyst engineered by metal–organic framework precursor for enhancing NO_x removal performance