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

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Title: Pt/CexPr1−xO2 (x = 1 or 0.9) NOx storage–reduction (NSR) catalysts
Authors: Rico Pérez, Verónica | Bueno López, Agustín | Kim, Dae Jung | Ji, Yaying | Crocker, Mark
Research Group/s: Materiales Carbonosos y Medio Ambiente
Center, Department or Service: Universidad de Alicante. Departamento de Química Inorgánica | Universidad de Alicante. Instituto Universitario de Materiales
Keywords: NOx storage reduction | Ceria | Doped ceria | Praseodymium | Pt–ceria interaction
Knowledge Area: Química Inorgánica
Issue Date: Feb-2015
Publisher: Elsevier
Citation: Applied Catalysis B: Environmental. 2015, 163: 313-322. doi:10.1016/j.apcatb.2014.08.016
Abstract: 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.
Sponsor: The financial support of Generalitat Valenciana (predoctoral stay BEFPI/2012), the Spanish Ministry of Economy and Competitiveness (Project CTQ2012-30703), and co-financing by FEDER resources is acknowledged. Partial financial support was also provided by the National Science Foundation and the U.S. Department of Energy (DOE) under award no. CBET-1258742.
ISSN: 0926-3373 (Print) | 1873-3883 (Online)
DOI: 10.1016/j.apcatb.2014.08.016
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2014 Elsevier B.V.
Peer Review: si
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