Thermal stability of vanadia-tungsta-titania catalysts in the SCR process

Madia, Giuseppe; Elsener, Martin; Koebel, Manfred; Raimondi, Fabio; Wokaun, Alexander

doi:10.1016/s0926-3373(02)00099-1

Cited by 170 publications

(138 citation statements)

References 19 publications

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“…In contrast to the V-loaded samples, the support material WT exhibited a SSA of 44 m 2 /g after calcination at 700 °C. This confirms the observation that vanadium assists the sintering of the support material [18]. It is also evident that a high vanadium content accelerates sintering, i.e.…”

Section: Characterizationsupporting

confidence: 88%

“…Madia et al examined the thermal stability of 1, 2 and 3 wt. % V2O5/WT [18]. The most active and thermally stable catalyst at 600 °C was found at 2 wt.…”

Section: Introductionmentioning

confidence: 98%

“…Extensive research has been undertaken to understand the different aspects of standard V-based SCR catalysts. These efforts were aimed at revealing mechanistic details such as the nature of the active centers and the rate determining steps [10][11][12][13][14][15][16][17], the origin of catalyst aging [18] and the electronic interactions between the various catalyst components and the poisoning phenomena [19][20][21]. For this purpose, parameters such as the synthesis of the TiO2 support material [22,23], the synthesis method, the loading and the nature of WO3 and V2O5 and the structural change upon thermal/hydrothermal treatment have been addressed.…”

Section: Introductionmentioning

confidence: 99%

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VOx Surface Coverage Optimization of V2O5/WO3-TiO2 SCR Catalysts by Variation of the V Loading and by Aging

et al. 2015

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V2O5/WO3-TiO2 selective catalytic reduction (SCR) catalysts with a V2O5 loading of 1.7, 2.0, 2.3, 2.6, 2.9, 3.2 and 3.5 wt. % were investigated in the fresh state and after hydrothermal aging at 600 °C for 16 h. The catalysts were characterized by means of nitrogen physisorption, X-ray diffraction and X-ray absorption spectroscopy. In the fresh state, the SCR activity increased with increasing V loading. Upon aging, the catalysts with up to 2.3 wt. % V2O5 exhibited higher NOx reduction activity than in the fresh state, while the catalysts with more than 2.6 wt. % V2O5 showed increasing deactivation tendencies. The observed activation and deactivation were correlated with the change of the VOx and WOx surface coverages. Only catalysts with a VOx coverage below 50% in the aged state did not show deactivation tendencies. With respect to tungsten, above one monolayer of WOx, WO3 particles were formed leading to loss of surface acidity, sintering, catalyst deactivation and early NH3 slip. An optimal compromise between activity and hydrothermal aging resistance could be obtained only with V2O5 between 2.0 and 2.6 wt. %.

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Section: Characterizationsupporting

confidence: 88%

“…Madia et al examined the thermal stability of 1, 2 and 3 wt. % V2O5/WT [18]. The most active and thermally stable catalyst at 600 °C was found at 2 wt.…”

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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VOx Surface Coverage Optimization of V2O5/WO3-TiO2 SCR Catalysts by Variation of the V Loading and by Aging

et al. 2015

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“…Commercially-available, anatase-type TiO 2 -supported V 2 O 5 catalysts with either WO 3 or MoO 3 as a structure stabilizer of the support and a surface acidity enhancer are typical for selective catalytic reduction (SCR) of NO x from relatively large scale stationary and mobile sources in the presence of N-containing reductants, such as gaseous NH 3 and aqueous urea [1,2]. They are usually formulated to 0.1-3% V 2 O 5 and 7-10% WO 3 or 6-10% MoO 3 [3][4][5][6][7][8], depending on industrial application target, and V 2 O 5 -WO 3 /TiO 2 systems are prevailed for such deNO x processes.…”

Section: Introductionmentioning

confidence: 99%

“…They are usually formulated to 0.1-3% V 2 O 5 and 7-10% WO 3 or 6-10% MoO 3 [3][4][5][6][7][8], depending on industrial application target, and V 2 O 5 -WO 3 /TiO 2 systems are prevailed for such deNO x processes. The overall NH 3 -SCR reaction with V 2 O 5 /TiO 2 -based catalysts could be adequately described by [5][6][7]:…”

Section: Introductionmentioning

confidence: 99%

The Role of Fe2O3 Species in Depressing the Formation of N2O in the Selective Reduction of NO by NH3 over V2O5/TiO2-Based Catalysts

Kim

Yang

2018

Catalysts

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Promotion of 2.73% Fe 2 O 3 in an in-house-made V 2 O 5 -WO 3 /TiO 2 (VWT) and a commercial V 2 O 5 -WO 3 /TiO 2 (c-VWT) has been investigated as a cost effective approach to the suppression of N 2 O formation in the selective catalytic reduction of NO by NH 3 (NH 3 -SCR). The promoted VWT and c-VWT catalysts all gave a significantly decreased N 2 O production at temperatures >400 • C compared to the unpromoted samples. However, such a promotion led to the loss in high temperature NO conversion, mainly due to the oxidation of NH 3 to N-containing gases, particularly NO. Characterization of the unpromoted and promoted catalysts using X-ray diffraction (XRD), NH 3 adsorption-desorption, and Raman spectroscopy techniques could explain the reason why the promotion showed much lower N 2 O formation levels at high temperatures. The addition of Fe 2 O 3 to c-VWT resulted in redispersion of the V 2 O 5 species, although this was not visible for 2.73% Fe 2 O 3 /VWT. The iron oxides exist as a highly-dispersed noncrystalline α-Fe 2 O 3 in the promoted catalysts. These Raman spectra had a new Raman signal that could be tentatively assigned to Fe 2 O 3 -induced tetrahedrally coordinated polymeric vanadates and/or surface V-O-Fe species with significant electronic interactions between the both metal oxides. Calculations of the monolayer coverage of each metal oxide and the surface total coverage are reasonably consistent with Raman measurements. The proposed vanadia-based surface polymeric entities may play a key role for the substantial reduction of N 2 O formed at high temperatures by NH 3 species adsorbed strongly on the promoted catalysts. This reaction is a main pathway to greatly suppress the extent of N 2 O formation in NH 3 -SCR reaction over the promoted catalysts.

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Flue Gases from Stationary Sources

Gabrielsson

Pedersen

2008

Handbook of Heterogeneous Catalysis

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The sections in this article are Emissions from Stationary Sources Drivers for Flue Gas Cleaning Technology The USA E urope A sia C hina J apan NO x Removal Technologies Nitrous Oxide (N 2 O) Selective Catalytic Reduction ( SCR ) SCR Technology SCR Catalysts Different Catalyst Types Choice of Carrier Optimization of Activity The Effect of Increasing V 2 O 5 Loading Activation Energy as a Function of Vanadium Content The Effect of Co‐Oxides SCR Reaction Mechanism for Vanadium Catalysts: the Eley–Rideal Route Global Kinetics The Importance of B rønsted Acidity The Influence of Reoxidation or NO 2 The Influence of Gas Composition on Reaction Rate The Influence of Water The Influence of O 2 Modeling Definition of Different Model Types Estimation of Interphase Mass Transfer Intraporous Mass Transfer Kinetic Expressions The Feasibility of Different Models Deactivation Chemical Poisoning Surface Fouling, Pore and Channel Clogging Sintering Catalyst Management and Regeneration SCR Catalyst Testing Laboratory‐ and Bench‐Scale Testing Pilot‐Scale Testing Slip‐Stream Reactors Full‐Scale Catalyst Testing Gas Sampling and Analysis Other Emissions Sulfur Removal The Wet Sulfuric Acid ( WSA ) Process and Combined WSA and De NO x ( SNOX ) Hydrogen Sulfide Carbon Monoxide Carbon Dioxide Hydrocarbons Dioxins Hg Oxidation and Capture Hg Oxidation Thermodynamics Hg Removal from Coal‐Fired Power Plants A Conventional Flue Gas Cleaning Processes B Sorbent Injection, Coal Additives, and Coal Blending Hg Oxidation Mechanism and Catalysis Alternative Processes Multipollutant Processes The DESONOX Process Other Combined Processes Catalytic Filters New Technologies Plasma‐Assisted Processes Photocatalytic Processes

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Thermal stability of vanadia-tungsta-titania catalysts in the SCR process

Cited by 170 publications

References 19 publications

VOx Surface Coverage Optimization of V2O5/WO3-TiO2 SCR Catalysts by Variation of the V Loading and by Aging

VOx Surface Coverage Optimization of V2O5/WO3-TiO2 SCR Catalysts by Variation of the V Loading and by Aging

The Role of Fe2O3 Species in Depressing the Formation of N2O in the Selective Reduction of NO by NH3 over V2O5/TiO2-Based Catalysts

Flue Gases from Stationary Sources

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