Structural Induced Effect of Potassium on the Reactivity of Vanadate Species in V2O5–WO3/TiO2 SCR-Catalyst

Siaka, Hermann Wilfried; Dujardin, Christophe; Moissette, Alain; Granger, Pascal

doi:10.1007/s11244-018-1103-2

Cited by 4 publications

(4 citation statements)

References 28 publications

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“…A detailed kinetic analysis reveals that NH 3 adsorption/desorption, NH 3 oxidation and DeNO x activity are all affected by K poisoning. Similar tendencies were demonstrated by Siaka et al [162], who claim that potassium preferentially neutralizes strong acid sites and alters V=O redox sites, leading to stabilization of well-dispersed VO x species. Contrasting with the results of Xie et al, Chen et al concluded that tungsten oxide can serve as a sacrificial agent protecting vanadia from severe K poisoning [163].…”

Section: Potassium and Calcium Poisoningsupporting

confidence: 84%

Tungsten-Based Catalysts for Environmental Applications

2021

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This review aims to give a general overview of the recent use of tungsten-based catalysts for wide environmental applications, with first some useful background information about tungsten oxides. Tungsten oxide materials exhibit suitable behaviors for surface reactions and catalysis such as acidic properties (mainly Brønsted sites), redox and adsorption properties (due to the presence of oxygen vacancies) and a photostimulation response under visible light (2.6–2.8 eV bandgap). Depending on the operating condition of the catalytic process, each of these behaviors is tunable by controlling structure and morphology (e.g., nanoplates, nanosheets, nanorods, nanowires, nanomesh, microflowers, hollow nanospheres) and/or interactions with other compounds such as conductors (carbon), semiconductors or other oxides (e.g., TiO2) and precious metals. WOx particles can be also dispersed on high specific surface area supports. Based on these behaviors, WO3-based catalysts were developed for numerous environmental applications. This review is divided into five main parts: structure of tungsten-based catalysts, acidity of supported tungsten oxide catalysts, WO3 catalysts for DeNOx applications, total oxidation of volatile organic compounds in gas phase and gas sensors and pollutant remediation in liquid phase (photocatalysis).

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Section: Potassium and Calcium Poisoningsupporting

confidence: 84%

Tungsten-Based Catalysts for Environmental Applications

2021

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“…Four peaks at 146, 396, 515, and 638 cm –1 were detected on the surface of all catalysts and were attributed to anatase TiO 2 , , which indicated that the structure of TiO 2 was not changed by the added K salt. The spectral peaks at 1013 cm –1 and 900–1000 cm –1 detected on the surface of the fresh catalyst were attributed to VO groups of monomeric and polymeric vanadyl species, respectively. , Generally, the monomeric vanadyl species exist predominantly on the TiO 2 surface by coverage of the basic sites with Ti–O–V . The peak at 1013 cm –1 was not detected on the K-poisoned catalysts, which meant that the monomeric VO groups may combine with the added K + or anion to generate V–O–K or V–O–e – .…”

Section: Results and Discussionmentioning

confidence: 99%

“…The spectral peaks at 1013 cm −1 and 900−1000 cm −1 detected on the surface of the fresh catalyst were attributed to V�O groups of monomeric and polymeric vanadyl species, respectively. 28,29 Generally, the monomeric vanadyl species exist predominantly on the TiO 2 surface by coverage of the basic sites with Ti−O−V. 30 The peak at 1013 cm −1 was not detected on the K-poisoned catalysts, which meant that the monomeric V�O groups may combine with the added K + or anion to generate V−O−K or V−O−e − .…”

Section: Textural Propertiesmentioning

confidence: 99%

Effect of Various Acid Anions on Potassium Poisoning and the Mechanism of Commercial V₂O₅–WO₃/TiO₂ Catalysts for SCR of NO_x

Zhang,

Miao,

Huang

et al. 2024

Ind. Eng. Chem. Res.

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The poisoning of K 2 O, KCl, and K 2 SO 4 on commercial V 2 O 5 −WO 3 /TiO 2 catalysts used for selective catalytic reduction (SCR) of NO x by NH 3 was investigated, respectively. The degree of inactivation observed in these catalysts poisoned with different forms of potassium follows K 2 O ≈ KCl > K 2 SO 4 . At 350 °C, the NO x conversion of the K 2 SO 4 poisoning catalyst (0.5 wt % K) was 53%, while that of the K 2 O and KCl poisoning catalysts was only 2 and 4%, respectively. The atomic ratio of V 5+ /V 4+ (0.76) and the proportion of adsorbed oxygen species (48%) on the surface of the K 2 SO 4 poisoning sample were higher than those of the K 2 O poisoning sample (0.64, 36%) and the KCl poisoning sample (0.66, 36%). The above phenomena were due to the different poisoning mechanisms caused by K 2 O, KCl, and K 2 SO 4 . K 2 O decreased the number of Brønsted and Lewis acid sites and, moreover, reduced V 5+ to V 4+ ; K in KCl preferred to occupy Brønsted acid sites and Cl in KCl reduced Lewis acid sites. SO 4 2− in K 2 SO 4 counteracted the impact of K on the surface acid sites and V 5+ of the poisoned catalyst and generated new Brønsted acid sites.

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“…At present, the commonly used NOx removal technology is selective catalytic reduction (SCR) [4][5][6][7] The widely used commercial V 2 O 5 -WO 3 (MoO 3 )/TiO 2 catalyst has some disadvantages, such as the toxicity of V 2 O 5 , high price and narrow reaction temperature ranges (300-400 1C). [8][9][10] Therefore, the design of a novel, non-toxic and low-cost denitration catalyst has attracted much attention, which can enhance the catalytic activity and widen the reaction temperature range.…”

Section: Introductionmentioning

confidence: 99%