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Structure-reactivity relationships in VOx/CexZr1−xO2 catalysts used for low-temperature NH3-SCR of NO

Paper ID Volume ID Publish Year Pages File Format Full-Text
45507 46413 2016 9 PDF Available
Title
Structure-reactivity relationships in VOx/CexZr1−xO2 catalysts used for low-temperature NH3-SCR of NO
Abstract

•5% V2O5/CexZr1−xO2 catalyze NH3-SCR of NO with highest GHSV at T ≤ 200 °C.•Most active sites are OCeOV(O)OZrO surface moieties.•V5+/V4+ and/or V4+/V3+ but no Ce4+/Ce3+ redox cycles are passed.

Supported catalysts with 5 wt.% V2O5 on CexZr1−xO2 (x = 1, 0.9, 0.8, 0.7, 0.5, 0.3 and 0) have been prepared and tested in selective catalytic reduction (SCR) of NO by NH3 between 100 and 300 °C at a GHSV of 70000 h−1. They were also characterized with regard to phase composition, structure of VOx sites and valence state of vanadium, cerium and zirconium using XRD, ICP-OES, XPS, UV–vis-DRS and EPR, partly in situ. V/Ce0.7Zr0.3O2 showed highest activity, N2 selectivity and stability with almost 100% NO conversion to N2 at 220 °C and no deactivation during 190 h on stream at 250 °C. Besides high V/(Ce + Zr) surface ratio, fast and reversible VOx redox cycles revealed to be essential for active catalysts, while Ce and Zr seem to stay tetravalent under reaction conditions. Both, catalytic activity as well as VOx reduction/reoxidation rates decrease in the order V/Ce0.7Zr0.3O2 > V/ZrO2 > V/CeO2. In the best catalyst V/Ce0.7Zr0.3O2, active VOx sites are effectively connected to the support surface, probably within OCeOV(O)OZrO moieties that may support oxygen transport, which is relevant for high SCR activity.

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Keywords
Supported V2O5 on CeO2; ZrO2 and CexZr1−xO2 catalysts; NH3-SCR of NO; In situ-UV–vis-DRS; In situ-EPR; Pseudo-in situ-XPS
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Structure-reactivity relationships in VOx/CexZr1−xO2 catalysts used for low-temperature NH3-SCR of NO
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 197, 15 November 2016, Pages 159–167
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us