Compensation or Aggravation: Pb and SO2 Copoisoning Effects over Ceria-Based Catalysts for NOx Reduction

Zou, Jingjing; Impeng, Sarawoot; Wang, Fuli; Lan, Tianwei; Wang, Lulu; Wang, Penglu; Zhang, Dengsong

doi:10.1021/acs.est.2c03653

Cited by 34 publications

(25 citation statements)

References 52 publications

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“…Subsequently, the adsorbed NH 3 species are gradually consumed after the introduction of 1000 ppm of NO and 5% O 2 , absorption bands corresponding to H 2 O appear around 1630 cm –1 as well as 3500 cm –1 (Figure S32), and adsorbed NO x species are hardly observed in the first 4 min of the SCR reaction when the NH 3 band intensity is significantly reduced, indicating that the adsorbed NH 3 reacts with gaseous NO at this time, i.e., the reaction follows the E-R mechanism. Finally, the surface of the Mn/ZrTi-A catalyst is covered by monodentate nitrate (1244 cm –1 ), adsorbed NO x (1590, 1619 cm –1 ), and a small amount of bidentate nitrate (1552 cm –1 ) . As for Mn/ZrTi-C (Figure b), the absorption bands at 1204, 1603, and 1435 cm –1 appear after preadsorption of NH 3 at 120 °C for 60 min, corresponding to NH 3 and NH 4 + species, respectively.…”

Section: Resultsmentioning

confidence: 93%

Improved N₂ Selectivity of MnO_x Catalysts for NO_x Reduction by Engineering Bridged Mn³⁺ Sites

et al. 2023

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Mn-based catalysts are promising for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures due to their excellent redox capacity. However, the N 2 selectivity of Mn-based catalysts is an urgent problem for practical application owing to excessive oxidizability. To solve this issue, we report a Mn-based catalyst using amorphous ZrTiO x as the support (Mn/ZrTi-A) with both excellent low-temperature NO x conversion and N 2 selectivity. It is found that the amorphous structure of ZrTiO x modulates the metal−support interaction for anchoring the highly dispersed active MnO x species and constructs a uniquely bridged Mn 3+ bonded with the support through oxygen linked to Ti 4+ and Zr 4+ , respectively, which regulates the optimal oxidizability of the MnO x species. As a result, Mn/ZrTi-A is not conducive to the formation of ammonium nitrate that readily decomposes to N 2 O, thus further increasing N 2 selectivity. This work investigates the role of an amorphous support in promoting the N 2 selectivity of a manganese-based catalyst and sheds light on the design of efficient low-temperature deNO x catalysts.

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Section: Resultsmentioning

confidence: 93%

Improved N₂ Selectivity of MnO_x Catalysts for NO_x Reduction by Engineering Bridged Mn³⁺ Sites

et al. 2023

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“…(002) = −1.80 eV since the more negative value indicated stronger adsorption according to previous research. 66,67 Interestingly, this interaction of CeO 2−x and SO 4 tended to occur at the oxygen vacancy sites rather than at the neighboring Ce as the sulfate ion would spontaneously move to the oxygen vacancy sites during the geometric optimization process. All of the calculated results are provided in Table 2.…”

Section: Theoretical Perspective Of the Sulfationmentioning

confidence: 99%

Insights into the Selective Transformation of Ceria Sulfation and Iron/Manganese Mineralization for Enhancing the Selective Recovery of Rare Earth Elements

Zhou

Xiao

Guo

et al. 2023

Environ. Sci. Technol.

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To cope with the urgent and unprecedented demands for rare earth elements (REEs) in sophisticated industries, increased attention has been paid to REE recovery from recycled streams. However, the similar geochemical behaviors of REEs and transition metals often result in poor separation performance due to nonselectivity. Here, a unique approach based on the selective transformation between ceria sulfation and iron/ manganese mineralization was proposed, leading to the enhancement of the selective separation of REEs. The mechanism of the selective transformation of minerals could be ascribed to the distinct geochemical and metallurgical properties of ions, resulting in different combinations of cations and anions. According to hardsoft acid-base (HSAB) theory, the strong Lewis acid of Ce(III) was inclined to combine with the hard base of sulfates (SO 4 2− ), while the borderline acid of Fe(II)/Mn(II) prefers to interact with oxygen ions (O 2-). Both in situ characterization and density functional theory (DFT) calculation further revealed that such selective transformation might trigger by the generation of an oxygen vacancy on the surface of CeO 2 , leading to the formation of Ce 2 (SO 4 ) 3 and Fe/Mn spinel. Although the electron density difference of the configurations (CeO 2−x -SO 4 , Fe 2 O 3−x -SO 4 , and MnO 2−x -SO 4 ) shared a similar direction of the electron transfer from the metals to the sulfate-based oxygen, the higher electron depletion of Ce (Q Ce = −1.91 e) than Fe (Q Fe = −1.66 e) and Mn (Q Mn = −1.64 e) indicated the higher stability in the Ce−O−S complex, resulting in the larger adsorption energy of CeO 2−x -SO 4 (−6.88 eV) compared with Fe 2 O 3−x -SO 4 (−3.10 eV) and MnO 2−x -SO 4 (−2.49 eV). This research provided new insights into the selective transformation of REEs and transition metals in pyrometallurgy and thus offered a new approach for the selective recovery of REEs from secondary resources.

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“…Previously, Zhang et al found that the copoisoning of K and phosphorus exhibited a detoxification effect on Fe 2 O 3 /TiO 2 catalysts due to the newly formed Brønsted acid sites provided by phosphate and the enhanced redox ability originated mainly from the Fe–O–P structure. The detoxification effects of heavy metals and phosphorus or SO 2 were also demonstrated on CeO 2 /TiO 2 catalysts. , However, the copoisoning mechanisms for V-based catalysts in the coexistence of arsenic and cadmium are barely explored.…”

Section: Introductionmentioning

confidence: 99%

“…The detoxification effects of heavy metals and phosphorus or SO 2 were also demonstrated on CeO 2 /TiO 2 catalysts. 29,30 However, the copoisoning mechanisms for V-based catalysts in the coexistence of arsenic and cadmium are barely explored. In this work, the detoxification effect of arsenic on the cadmium-poisoned V 2 O 5 /TiO 2 (VTi) catalyst was reported.…”

Section: Introductionmentioning

confidence: 99%

Extraordinary Detoxification Effect of Arsenic on the Cadmium-Poisoned V₂O₅/TiO₂ Catalyst for Selective Catalytic Reduction of NO_x by NH₃

Jiang

Yin

et al. 2023

ACS EST Eng.

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Arsenic has been found as a serious toxicant for the catalysts in the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). However, the detoxification effect of arsenic on the cadmium-poisoned V 2 O 5 /TiO 2 catalyst was found in this work. With an arsenic loading of 1.8 wt %, the NO x conversion over cadmium-poisoned V 2 O 5 /TiO 2 increased from 45.1 to 88.3% at 350 °C under a GHSV of 300,000 h −1 . Meantime, the adverse effect on N 2 selectivity caused by arsenic was reduced. The catalyst characterization manifests that the surface VO xactive sites were liberated from the restriction of cadmium due to the interaction between cadmium and arsenic. More importantly, it was found that the SCR performance of the catalysts was highly dependent on the surface VO x sites. In situ experiments proved that the released surface VO x species could not only provide the Lewis sites for the NH 3 adsorption but also dominate the redox cycle (V 5+ ↔ V 4+ ) during the NH 3 -SCR process. We believe that this study can inspire directions for the design of NH 3 -SCR catalysts with superior resistance to different poisons. KEYWORDS: NH 3 -SCR, V 2 O 5 /TiO 2 , cadmium and arsenic, VO x sites, redox cycle

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Compensation or Aggravation: Pb and SO₂ Copoisoning Effects over Ceria-Based Catalysts for NO_x Reduction

Cited by 34 publications

References 52 publications

Improved N₂ Selectivity of MnO_x Catalysts for NO_x Reduction by Engineering Bridged Mn³⁺ Sites

Improved N₂ Selectivity of MnO_x Catalysts for NO_x Reduction by Engineering Bridged Mn³⁺ Sites

Insights into the Selective Transformation of Ceria Sulfation and Iron/Manganese Mineralization for Enhancing the Selective Recovery of Rare Earth Elements

Extraordinary Detoxification Effect of Arsenic on the Cadmium-Poisoned V₂O₅/TiO₂ Catalyst for Selective Catalytic Reduction of NO_x by NH₃

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Compensation or Aggravation: Pb and SO2 Copoisoning Effects over Ceria-Based Catalysts for NOx Reduction

Cited by 34 publications

References 52 publications

Improved N2 Selectivity of MnOx Catalysts for NOx Reduction by Engineering Bridged Mn3+ Sites

Improved N2 Selectivity of MnOx Catalysts for NOx Reduction by Engineering Bridged Mn3+ Sites

Insights into the Selective Transformation of Ceria Sulfation and Iron/Manganese Mineralization for Enhancing the Selective Recovery of Rare Earth Elements

Extraordinary Detoxification Effect of Arsenic on the Cadmium-Poisoned V2O5/TiO2 Catalyst for Selective Catalytic Reduction of NOx by NH3

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Compensation or Aggravation: Pb and SO₂ Copoisoning Effects over Ceria-Based Catalysts for NO_x Reduction

Improved N₂ Selectivity of MnO_x Catalysts for NO_x Reduction by Engineering Bridged Mn³⁺ Sites

Improved N₂ Selectivity of MnO_x Catalysts for NO_x Reduction by Engineering Bridged Mn³⁺ Sites

Extraordinary Detoxification Effect of Arsenic on the Cadmium-Poisoned V₂O₅/TiO₂ Catalyst for Selective Catalytic Reduction of NO_x by NH₃