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Pt/CexPr1−xO2 (x = 1 or 0.9) NOx storage–reduction (NSR) catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
44884 46375 2015 10 PDF Available
Title
Pt/CexPr1−xO2 (x = 1 or 0.9) NOx storage–reduction (NSR) catalysts
Abstract

•Model Pt/Ce0.9Pr0.1O2 and Pt/CeO2 NOx storage–reduction catalysts were prepared.•Presence of Pr in the ceria lattice increased the concentration of defect sites.•Pt/Ce0.9Pr0.1O2 samples afforded higher NOx conversions than their Pt/CeO2 analogs.•Superior performance of Pt/Ce0.9Pr0.1O2 is due to higher NOx storage efficiency.•Pr doping destabilizes adsorbed NOx during rich periods, improving catalyst regeneration.

Model Pt/Ce0.9Pr0.1O2 and Pt/CeO2 NOx storage–reduction catalysts were prepared via nitrate calcination, co-precipitation and carbon-templating routes. Raman spectroscopic data obtained on the catalysts indicated that the introduction of praseodymium into the ceria lattice increased the concentration of defect sites (vacancies), arising from the higher reducibility of the Pr4+ cation compared to Ce4+. For the Pr-promoted samples, H2-TPR profiles contained high temperature bulk reduction peaks which were less pronounced compared with their ceria analogs, indicating that the presence of praseodymium enhances oxygen mobility due to the creation of lattice defects. Under lean-rich cycling conditions, the cycle-averaged NOx conversion of the Pt/Ce0.9Pr0.1O2 samples was in each case substantially higher than that of the Pt/CeO2 analog, amounting to a difference of 10–15% in the absolute NOx conversion in some cases. According to DRIFTS data, a double role can be assigned to Pr doping; on the one hand, Pr accelerates the oxidation of adsorbed NOx species during the lean periods. On the other hand, Pr doping destabilizes the adsorbed NOx species during the rich periods, and the kinetics of nitrate decomposition are faster on Pt/Ce0.9Pr0.1O2, leading to improved catalyst regeneration. These results suggest that ceria-based mixed oxides incorporating Pr are promising materials for NOx storage–reduction catalysts intended for low temperature operation.

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Keywords
NOx storage reduction; Ceria; Doped ceria; Praseodymium; Pt–ceria interaction
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Pt/CexPr1−xO2 (x = 1 or 0.9) NOx storage–reduction (NSR) catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 163, February 2015, Pages 313–322
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