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

Verónica Rico-Pérez; Agustín Bueno-López; Dae Jung Kim; Yaying Ji; Mark Crocker

doi:10.1016/j.apcatb.2014.08.016

Pt/Ce_xPr_1-xO₂ (x=1 or 0.9) NO_x storage-reduction (NSR) catalysts

Verónica Rico-Pérez, Agustín Bueno-López, Dae Jung Kim, Yaying Ji, Mark Crocker

Chemistry

Research output: Contribution to journal › Article › peer-review

15 Citations (SciVal)

Abstract

Model Pt/Ce_0.9Pr_0.1O₂ and Pt/CeO₂ NO_x 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 NO_x conversion of the Pt/Ce_0.9Pr_0.1O₂ samples was in each case substantially higher than that of the Pt/CeO₂ analog, amounting to a difference of 10-15% in the absolute NO_x 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 NO_x species during the lean periods. On the other hand, Pr doping destabilizes the adsorbed NO_x species during the rich periods, and the kinetics of nitrate decomposition are faster on Pt/Ce_0.9Pr_0.1O₂, leading to improved catalyst regeneration. These results suggest that ceria-based mixed oxides incorporating Pr are promising materials for NO_x storage-reduction catalysts intended for low temperature operation.

Original language	English
Pages (from-to)	313-322
Number of pages	10
Journal	Applied Catalysis B: Environmental
Volume	163
DOIs	https://doi.org/10.1016/j.apcatb.2014.08.016
State	Published - Feb 2015

Bibliographical note

Funding Information:
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 . However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE.

Keywords

Ceria
Doped ceria
Praseodymium
Pt-ceria interaction

ASJC Scopus subject areas

Catalysis
Environmental Science (all)
Process Chemistry and Technology

Access to Document

10.1016/j.apcatb.2014.08.016

Cite this

@article{8c0b1b9800a54eef87d5c79bd600a1ee,

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 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.",

keywords = "Ceria, Doped ceria, Praseodymium, Pt-ceria interaction",

author = "Ver{\'o}nica Rico-P{\'e}rez and Agust{\'i}n Bueno-L{\'o}pez and Kim, {Dae Jung} and Yaying Ji and Mark Crocker",

note = "Funding Information: 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 . However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE.",

year = "2015",

month = feb,

doi = "10.1016/j.apcatb.2014.08.016",

language = "English",

volume = "163",

pages = "313--322",

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TY - JOUR

T1 - Pt/CexPr1-xO2 (x=1 or 0.9) NOx storage-reduction (NSR) catalysts

AU - Rico-Pérez, Verónica

AU - Bueno-López, Agustín

AU - Kim, Dae Jung

AU - Ji, Yaying

AU - Crocker, Mark

N1 - Funding Information: 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 . However, any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the DOE.

PY - 2015/2

Y1 - 2015/2

N2 - 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.

AB - 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.

KW - Ceria

KW - Doped ceria

KW - Praseodymium

KW - Pt-ceria interaction

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JO - Applied Catalysis B: Environmental

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