Promoted V 2 O 5 /TiO 2 catalysts for selective catalytic reduction of NO with NH 3 at low temperatures

Putluru, Siva Sankar Reddy; Schill, Leonhard; Godiksen, Anita; Poreddy, Raju; Mossin, Susanne; Jensen, Anker Degn; Fehrmann, Rasmus

doi:10.1016/j.apcatb.2015.10.044

Cited by 137 publications

(58 citation statements)

References 35 publications

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“…Vanadium‐based materials play an important role in heterogeneous catalysis. Redox properties present in vanadium oxides are very useful to promote significant chemical processes, like oxidations, ammoxidations and reductions . An important parameter that induces catalytic properties in vanadium‐based materials is the support's surface coverage.…”

Section: Introductionmentioning

confidence: 99%

“…Redox properties present in vanadium oxides are very useful to promote significant chemical processes, like oxidations, [1,2] ammoxidations [3,4] and reductions. [5,6] An important parameter that induces catalytic properties in vanadiumbased materials is the support's surface coverage. In some specific cases, like oxidation of methanol, formation of different products is favored according to vanadium species formed on the active surface.…”

Section: Introductionmentioning

confidence: 99%

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Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

et al. 2019

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Supported transition metal catalysts have been extensively applied to oxidative and reductive processes. The understanding of surface speciation and active site‐support interactions in these materials play a substantial role in developing improved heterogeneous catalysts. Herein, a series of impregnated 3D ferrierite and 2D ITQ‐6 siliceous supports with variable loading of vanadium oxide was prepared. Chemical and structural properties of the materials were studied by X‐ray diffraction, N2 physisorption, inductively coupled plasma – optical emission spectrometry, X‐ray absorption, Fourier transform infrared and diffuse reflectance UV‐vis spectroscopies, and temperature‐programmed reduction with H2. Reactivity of the catalyst surface, associated with the incidence of isolated silanol groups, was found to be more effective when vanadium oxides were better dispersed and stabilized than increases in surface area. Differences in activation and the oxidation state dynamic behavior of active sites were then probed by methanol oxidation as a model reaction monitored by in situ FTIR spectroscopy and XANES/MS. By applying isothermal periods of reaction under non‐oxidizing atmosphere and regeneration of catalysts by O2, it was found that, even at distinct rates, all types of sites are accessible during reaction, since a complete reduction to V4+ was observed. However, reoxidation of sites to V5+ is limited and sensitive to the different vanadium species on the surface, and probably, the determinant factor of the distinct V5+/V4+ equilibrium reached for the catalysts when the reaction is carried out under constant oxidizing atmosphere.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

et al. 2019

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“…In catalytic applications, heteropolyacids, H 4 SiW 12 O 40 (HSiW for short), is well‐known for its strong acidity and provides abundant acid sites, which can be serve for the adsorption of NH 3. HSiW with a unique acid property confirms the effect of acidity and oxidability on the catalytic performance, and the amount of HSiW is a key factor that determines the deNO x efficiency of catalysts. Therefore, the high loading of HSiW is indispensable to accomplish the increased activity of the catalysts and the method is similar to Madia and Okumura by increasing the loading of active components.…”

Section: Introductionmentioning

confidence: 94%

Silicotungstic acid modified Ce‐Fe‐O_x catalyst for selective catalytic reduction of NO_x with NH₃: Effect of the amount of HSiW

Song

Xing

Zhang

et al. 2019

Applied Organom Chemis

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The HSiW(x)/Ce‐Fe catalysts were used to research the effect of silicotungstic acid contents on the catalytic activity in the selective catalytic reduction of NOx with NH3. Doping different contents of silicotungstic acid affected surface species and redox property as well as the catalytic activity. With the increasing amount of HSiW (x = 5%, 10% and 20%), the redox reaction between Fe3+/Fe2+ and Ce4+/Ce3+ enhanced, which could improve the ratio of Ce3+ and Fe3+. And then, more Ce3+ increased the ratio of chemisorbed oxygen (Oα). Besides, the type and strength of acid sites over HSiW(x)/Ce‐Fe was affected by the HSiW contents. These factors facilitated the catalytic performance. Thus, the NOx conversion of HSiW(x)/Ce‐Fe(x = 20%) was higher than 90%, which maintained in a wide temperature range between 200 and 400 °C.

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“…Tail-end operation at the biomass co-fired Amager plant in Denmark indeed showed promising results between 2010 and 2012 [44]. Laboratory studies by Putluru et al [46] have furthermore shown that heteropoly acid (instead of WO 3 )-promoted catalysts with a high (3 and 5 wt.%) vanadia loading can retain more than 90% of their activity at 225 • C when poisoned with 100 µmol K g −1 catalyst . A corresponding WO 3 promoted catalyst lost almost 50% of its activity.…”

Section: Tail-end Placement Of the Scr Unitmentioning

confidence: 99%

Strategies of Coping with Deactivation of NH3-SCR Catalysts Due to Biomass Firing

Schill¹,

Fehrmann²

2018

Catalysts

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Firing of biomass can lead to rapid deactivation of the vanadia-based NH3-SCR catalyst, which reduces NOx to harmless N2. The deactivation is mostly due to the high potassium content in biomasses, which results in submicron aerosols containing mostly KCl and K2SO4. The main mode of deactivation is neutralization of the catalyst’s acid sites. Four ways of dealing with high potassium contents were identified: (1) potassium removal by adsorption, (2) tail-end placement of the SCR unit, (3) coating SCR monoliths with a protective layer, and (4) intrinsically potassium tolerant catalysts. Addition of alumino silicates, often in the form of coal fly ash, is an industrially proven method of removing K aerosols from flue gases. Tail-end placement of the SCR unit was also reported to result in acceptable catalyst stability; however, flue-gas reheating after the flue gas desulfurization is, at present, unavoidable due to the lack of sulfur and water tolerant low temperature catalysts. Coating the shaped catalysts with thin layers of, e.g., MgO or sepiolite reduces the K uptake by hindering the diffusion of K+ into the catalyst pore system. Intrinsically potassium tolerant catalysts typically contain a high number of acid sites. This can be achieved by, e.g., using zeolites as support, replacing WO3 with heteropoly acids, and by preparing highly loaded, high surface area, very active V2O5/TiO2 catalyst using a special sol-gel method.

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Promoted V 2 O 5 /TiO 2 catalysts for selective catalytic reduction of NO with NH 3 at low temperatures

Cited by 137 publications

References 35 publications

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Silicotungstic acid modified Ce‐Fe‐O_x catalyst for selective catalytic reduction of NO_x with NH₃: Effect of the amount of HSiW

Strategies of Coping with Deactivation of NH3-SCR Catalysts Due to Biomass Firing

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Promoted V 2 O 5 /TiO 2 catalysts for selective catalytic reduction of NO with NH 3 at low temperatures

Cited by 137 publications

References 35 publications

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Insights into Redox Dynamics of Vanadium Species Impregnated in Layered Siliceous Zeolitic Structures during Methanol Oxidation Reactions

Silicotungstic acid modified Ce‐Fe‐Ox catalyst for selective catalytic reduction of NOx with NH3: Effect of the amount of HSiW

Strategies of Coping with Deactivation of NH3-SCR Catalysts Due to Biomass Firing

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Silicotungstic acid modified Ce‐Fe‐O_x catalyst for selective catalytic reduction of NO_x with NH₃: Effect of the amount of HSiW