Sol-gel one-pot synthesis of efficient and environmentally friendly iron-based catalysts for NH 3 -SCR

Zhao, Kun; Meng, Jie; Lu, Jiangyin; Yang, He; Huang, Hui-Zi; Tang, Zhicheng; Zhen, Xinping

doi:10.1016/j.apsusc.2018.03.160

Cited by 45 publications

(14 citation statements)

References 41 publications

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“…The particles in Fe85Ce10W5-CP-CA have an outstanding distribution, contributing to the smaller pores and larger pore volume, which is beneficial to mass transfer and diffusion. Meanwhile, the diffusion of reactant gases and product gases among the pores of catalysts is important for NH3-SCR reaction [31][32][33]. In addition, the removal of nitrate also decreases the particles' average diameter of Fe85Ce10W5-CP-CA as calculated from the SEM in Figures 4C,D, which is in accordance with the particle sizes calculated according to the Scherrer equation.…”

Section: Scanning Electron Microscopy (Sem)supporting

confidence: 80%

“…Figure 5 displays the N 2 adsorption-desorption isotherms, the pore size distributions of Fe 85 Ce 10 W 5 -CP-CA and Fe 85 Ce 10 W 5 -CP-CA(NA 1.0 ), and their NO x conversions over per surface area in one hour (mg/(m 2 •h)). As can be observed, the isotherm of Fe 85 Ce 10 W 5 -CP-CA(NA1.0) can be recognized as a type IV N2 adsorption/desorption isotherm according to the International Union of Pure and Applied Chemistry (IUPAC) classification, and it presents mainly meso-pores (2-50 nm), however, the hysteresis loops of Fe85Ce10W5-CP-CA(NA1.0) and Fe85Ce10W5-CP-CA are the H2 and H1 type [32,34], respectively. This demonstrates that the removal of nitrate promotes the formation of meso-pores in magnetic, and the Fe85Ce10W5-CP-CA catalyst shows uniform and regular meso-pores, which was confirmed by the results of the pore diameter distribution in Figure 5B [35].…”

Section: N 2 Adsorption-desorptionmentioning

confidence: 99%

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The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

et al. 2020

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Sol-gel spread self-combustion is the burning of the complexing agent in dried gel and the oxidant. Meanwhile, high temperature takes place during the combustion process, which is harmful to the pore structure of the catalyst. The nitrate from metal nitrate precursors as an oxidant could participate in the spread of the self-combustion process. Therefore, the influence of nitrate from metal nitrate on the spread self-combustion of an iron–cerium–tungsten citric acid gel and its catalytic performance of NOx reduction were investigated by removing nitrate via the dissolution of washing co-precipitation with citric acid and re-introducing nitric acid into the former solution. It was found that the removal of nitrate contributes to enhancing the NH3–SCR activity of the magnetic mixed oxide catalyst. The NOx reduction efficiency was close to 100% for Fe85Ce10W5–CP–CA at 250 °C while the highest was only 80% for the others. The results of thermal analysis demonstrate that the spread self-combustion process of citric acid dried gel is enhanced by re-introducing nitric acid into the citric acid dissolved solution when compared with the removal of nitrate. In addition, the removal of nitrate helps in the formation of γ-Fe2O3 crystallite in the catalyst, refining the particle size of the catalyst and increasing its pore volume. The removal of nitrate also contributes to the formation of Lewis acid sites and Brønsted acid sites on the surface of the catalyst compared with the re-introduction of nitric acid. The in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) demonstrates that both Eley–Rideal (E–R) and Langmuir–Hinshelwood (L–H) mechanisms exist over Fe85Ce10W5–CP–CA at 250 °C with E–R as its main mechanism.

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Section: Scanning Electron Microscopy (Sem)supporting

confidence: 80%

Section: N 2 Adsorption-desorptionmentioning

confidence: 99%

The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

et al. 2020

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“…The DeNO x mechanism was further analyzed as below. It was confirmed that an iron-based mixed oxide catalyst would follow the Langmuir-Hinshelwood mechanism under 250 • C, where both NH 3 and NO would be adsorbed to all of the acid sites and then transformed to the corresponding intermediate [36]. The dramatic decrease of acid quantity for NiFe-600 resulted in the absence of adsorption of the reactant; accordingly, the low-temperature activity decreased.…”

Section: -mentioning

confidence: 85%

NOx Removal by Selective Catalytic Reduction with Ammonia over a Hydrotalcite-Derived NiFe Mixed Oxide

Wang

Zou

et al. 2018

Catalysts

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A series of NiFe mixed oxide catalysts were prepared via calcining hydrotalcite-like precursors for the selective catalytic reduction of nitrogen oxides (NOx) with NH3 (NH3-SCR). Multiple characterizations revealed that catalytic performance was highly dependent on the phase composition, which was vulnerable to the calcination temperature. The MOx phase (M = Ni or Fe) formed at a lower calcination temperature would induce more favorable contents of Fe2+ and Ni3+ and as a result contribute to the better redox capacity and low-temperature activity. In comparison, NiFe2O4 phase emerged at a higher calcination temperature, which was expected to generate more Fe species on the surface and lead to a stable structure, better high-temperature activity, preferable SO2 resistance, and catalytic stability. The optimum NiFe-500 catalyst incorporated the above virtues and afforded excellent denitration (DeNOx) activity (over 85% NOx conversion with nearly 98% N2 selectivity in the region of 210–360 °C), superior SO2 resistance, and catalytic stability.

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“…It is widely accepted that lower reduction temperatures denoted to stronger redox properties. The peaks observed at 355°C and 337°C could be assigned to the reduction of MnO [53] The results illustrate that the addition of Fe could greatly enhance the redox properties of the MnÀ Eu-550 catalyst, which is favorable for the completion of the catalytic cycle in SCR reactions. [54] In addition, the areas of the reduction peaks of the MnÀ EuÀ Fe(1)-500 catalyst were much larger than those of the MnÀ EuÀ Fe(1)-550 catalyst.…”

Section: Resultsmentioning

confidence: 80%

“…The results of H 2 -TPR experiments for the MnÀ EuÀ Fe(x)-y catalysts are shown in Figure 11. [53] The results illustrate that the addition of Fe could greatly enhance the redox properties of the MnÀ Eu-550 catalyst, which is favorable for the completion of the catalytic cycle in SCR reactions. However, the reduction behaviors for all of the catalysts were quite different.…”

Section: Xpsmentioning

confidence: 90%

Improved Low‐Temperature Activity and H₂O Resistance of Fe‐Doped Mn−Eu Catalysts for NO Removal by NH₃−SCR

et al. 2019

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Novel MnÀ EuÀ Fe catalysts were prepared via co-precipitation method for NO x removal by selective catalytic reduction with NH 3 (NH 3 À SCR). The MnÀ EuÀ Fe(1)-500 catalyst possessed the highest level of low-temperature activity, giving 98 % NO conversion at 100°C. This catalyst also exhibited excellent H 2 O resistance capacity, even at a high gas hourly space velocity (GHSV) of 75,000 h À 1 . The NO conversion still maintained at approximately 90 % in the presence of 15 % H 2 O at 230°C after 50 h, and the adverse effects of H 2 O could be quickly eliminated after the removal of H 2 O. Detailed characterization and analysis indicated that strong interactions among Mn, Eu and Fe resulted in the excellent low-temperature SCR activity and H 2 O resistance of the MnÀ EuÀ Fe(1)-500 catalyst. The strong interactions lead to larger specific surface area, higher concentrations of Mn 4 + , Fe 3 + and O α ; improved redox properties, increased acid sites and acid strength, and more adsorption amounts of NO/NH 3 in the presence of H 2 O. The MnÀ EuÀ Fe(1)-500 catalyst is a potential future catalyst for low-temperature NO x removal derived from high-H 2 O-content flue gases of natural gas combustion.

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Sol-gel one-pot synthesis of efficient and environmentally friendly iron-based catalysts for NH 3 -SCR

Cited by 45 publications

References 41 publications

The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

NOx Removal by Selective Catalytic Reduction with Ammonia over a Hydrotalcite-Derived NiFe Mixed Oxide

Improved Low‐Temperature Activity and H₂O Resistance of Fe‐Doped Mn−Eu Catalysts for NO Removal by NH₃−SCR

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Sol-gel one-pot synthesis of efficient and environmentally friendly iron-based catalysts for NH 3 -SCR

Cited by 45 publications

References 41 publications

The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

The Role of Nitrate on the Sol-Gel Spread Self-Combustion Process and Its Effect on the NH3-SCR Activity of Magnetic Iron-Based Catalyst

NOx Removal by Selective Catalytic Reduction with Ammonia over a Hydrotalcite-Derived NiFe Mixed Oxide

Improved Low‐Temperature Activity and H2O Resistance of Fe‐Doped Mn−Eu Catalysts for NO Removal by NH3−SCR

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Improved Low‐Temperature Activity and H₂O Resistance of Fe‐Doped Mn−Eu Catalysts for NO Removal by NH₃−SCR