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Title: Effects of Molecular and Electronic Structures in CoO x/CeO 2 Catalysts on NO Reduction by CO

Abstract

Ceria-supported transition metal oxide (such as CoO x) catalysts are promising, more cost-effective candidates to replace platinum group metal catalysts in the NO reduction process. A series of CoO x (0.2–31.3 Co/nm 2) catalysts supported on CeO 2 were prepared by the incipient wetness impregnation method and were tested for NO reduction by CO reaction in this work. Various characterization techniques, including Brunauer–Emmett–Teller, Raman spectroscopy, powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to investigate the molecular and electronic structures of CoO x/CeO 2 catalysts. It was observed that there are structural changes with varied Co loadings, such as (1) sub-monolayer: <2.3 Co/nm 2, (2) monolayer: 2.3–2.7 Co/nm 2, and (3) over-monolayer: >2.7 Co/nm 2. The highest molar rate was observed at the 2.7 Co/nm2 sample. In the case of over-monolayer samples, such as 7.1 Co/nm 2, the oxidation state of Co affected the catalytic activity. Using in situ XAS, an oxidation state change from Co 3+ to Co 2+ between 200 and 300 °C was identified. Catalyst deactivation was also affected by the change of Co oxidation states from the fresh sample (Co 3+) to the used sample (Comore » 3+/Co 2+). N 2O formation and decomposition were affected by the reaction temperature in a two-step procedure, where NO converts into N 2: (1) NO → N 2O and (2) N 2O → N 2. N 2 selectivity monotonically increased with an increasing reaction temperature between 200 and 400 °C. Furthermore, the results provided several structure–property relationships and a possible reaction mechanism for NO reduction by CO reaction over CoO x/CeO 2 catalysts.« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [2]; ORCiD logo [3]; ORCiD logo [1]
  1. Stony Brook Univ., Stony Brook, NY (United States)
  2. Seoul National Univ., Seoul (Republic of Korea)
  3. Stony Brook Univ., Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1508522
Report Number(s):
BNL-211570-2019-JAAM
Journal ID: ISSN 1932-7447
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 123; Journal Issue: 12; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION

Citation Formats

Zhang, Shuhao, Li, Yuanyuan, Huang, Jiahao, Lee, Jaeha, Kim, Do Heui, Frenkel, Anatoly I., and Kim, Taejin. Effects of Molecular and Electronic Structures in CoOx/CeO2 Catalysts on NO Reduction by CO. United States: N. p., 2019. Web. doi:10.1021/acs.jpcc.8b12442.
Zhang, Shuhao, Li, Yuanyuan, Huang, Jiahao, Lee, Jaeha, Kim, Do Heui, Frenkel, Anatoly I., & Kim, Taejin. Effects of Molecular and Electronic Structures in CoOx/CeO2 Catalysts on NO Reduction by CO. United States. doi:10.1021/acs.jpcc.8b12442.
Zhang, Shuhao, Li, Yuanyuan, Huang, Jiahao, Lee, Jaeha, Kim, Do Heui, Frenkel, Anatoly I., and Kim, Taejin. Mon . "Effects of Molecular and Electronic Structures in CoOx/CeO2 Catalysts on NO Reduction by CO". United States. doi:10.1021/acs.jpcc.8b12442.
@article{osti_1508522,
title = {Effects of Molecular and Electronic Structures in CoOx/CeO2 Catalysts on NO Reduction by CO},
author = {Zhang, Shuhao and Li, Yuanyuan and Huang, Jiahao and Lee, Jaeha and Kim, Do Heui and Frenkel, Anatoly I. and Kim, Taejin},
abstractNote = {Ceria-supported transition metal oxide (such as CoOx) catalysts are promising, more cost-effective candidates to replace platinum group metal catalysts in the NO reduction process. A series of CoOx (0.2–31.3 Co/nm2) catalysts supported on CeO2 were prepared by the incipient wetness impregnation method and were tested for NO reduction by CO reaction in this work. Various characterization techniques, including Brunauer–Emmett–Teller, Raman spectroscopy, powder X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were used to investigate the molecular and electronic structures of CoOx/CeO2 catalysts. It was observed that there are structural changes with varied Co loadings, such as (1) sub-monolayer: <2.3 Co/nm2, (2) monolayer: 2.3–2.7 Co/nm2, and (3) over-monolayer: >2.7 Co/nm2. The highest molar rate was observed at the 2.7 Co/nm2 sample. In the case of over-monolayer samples, such as 7.1 Co/nm2, the oxidation state of Co affected the catalytic activity. Using in situ XAS, an oxidation state change from Co3+ to Co2+ between 200 and 300 °C was identified. Catalyst deactivation was also affected by the change of Co oxidation states from the fresh sample (Co3+) to the used sample (Co3+/Co2+). N2O formation and decomposition were affected by the reaction temperature in a two-step procedure, where NO converts into N2: (1) NO → N2O and (2) N2O → N2. N2 selectivity monotonically increased with an increasing reaction temperature between 200 and 400 °C. Furthermore, the results provided several structure–property relationships and a possible reaction mechanism for NO reduction by CO reaction over CoOx/CeO2 catalysts.},
doi = {10.1021/acs.jpcc.8b12442},
journal = {Journal of Physical Chemistry. C},
number = 12,
volume = 123,
place = {United States},
year = {2019},
month = {3}
}

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This content will become publicly available on March 4, 2020
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