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Title: Structural and chemical state of doped and impregnated mesoporous Ni/CeO 2 catalysts for the water-gas shift

Abstract

Mesoporous Ni/CeO 2 catalysts of variable loadings were prepared using in-situ doping and impregnation synthesis techniques. The catalysts were found to exhibit activity for the water-gas shift (WGS) reaction, particularly at temperatures above 250 °C. Structural, electronic, and surface chemical characterizations of the materials were carried out using in-situ X-ray diffraction (XRD), in-situ X-ray absorption (XANES), and in-situ infrared (DRIFTS) techniques. The effects of metal loading and preparation method on these properties were studied in order to develop a more complete understanding of the design and application of Ni-loaded mesoporous CeO 2 catalysts. For WGS reaction activity, the in-situ doping method was observed to be superior, and overall activity was observed to increase with increasing metal loadings. Simple normalization of activity data to nominal nickel content revealed a trend favoring lower loadings, indicating higher activity per unit nickel. The reduction of the catalyst is observed with increasing reaction temperature (Ni 2+ → Ni°, Ce 4+ → Ce 3+) while the active states of all catalysts were identified as a stable, partially reduced ceria fluorite lattice (Ce 4+/Ce 3+) with Ni 2+ and Ni°. In Situ DRIFTS showed nearly identical surface chemistry for both doped and impregnated samples, likely involving anmore » associative pathway at lower temperatures and a redox pathway at higher temperatures. Structural properties and surface chemistry were observed to depend both on metal loading and preparation method. As a result, nickel loadings as low as 1 wt% prepared by in-situ doping were found to display the most favorable metal-support interactions for the WGS reaction.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4];  [4]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [4]
  1. Stony Brook Univ., Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Univ. of Connecticut, Storrs, CT (United States)
  3. Technical Univ. of Catalonia, Barcelona (Spain)
  4. 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:
1482568
Report Number(s):
BNL-209468-2018-JAAM
Journal ID: ISSN 0926-860X
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
Applied Catalysis. A, General
Additional Journal Information:
Journal Volume: 567; Journal Issue: C; Journal ID: ISSN 0926-860X
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Water-gas shift; Ceria; Nickel; Mesoporous; In situ

Citation Formats

Vovchok, Dimitriy, Guild, Curtis J., Llorca, Jordi, Palomino, Robert M., Waluyo, Iradwikanari, Rodriguez, José A., Suib, Steven L., and Senanayake, Sanjaya D. Structural and chemical state of doped and impregnated mesoporous Ni/CeO2 catalysts for the water-gas shift. United States: N. p., 2018. Web. doi:10.1016/j.apcata.2018.08.026.
Vovchok, Dimitriy, Guild, Curtis J., Llorca, Jordi, Palomino, Robert M., Waluyo, Iradwikanari, Rodriguez, José A., Suib, Steven L., & Senanayake, Sanjaya D. Structural and chemical state of doped and impregnated mesoporous Ni/CeO2 catalysts for the water-gas shift. United States. doi:10.1016/j.apcata.2018.08.026.
Vovchok, Dimitriy, Guild, Curtis J., Llorca, Jordi, Palomino, Robert M., Waluyo, Iradwikanari, Rodriguez, José A., Suib, Steven L., and Senanayake, Sanjaya D. Wed . "Structural and chemical state of doped and impregnated mesoporous Ni/CeO2 catalysts for the water-gas shift". United States. doi:10.1016/j.apcata.2018.08.026. https://www.osti.gov/servlets/purl/1482568.
@article{osti_1482568,
title = {Structural and chemical state of doped and impregnated mesoporous Ni/CeO2 catalysts for the water-gas shift},
author = {Vovchok, Dimitriy and Guild, Curtis J. and Llorca, Jordi and Palomino, Robert M. and Waluyo, Iradwikanari and Rodriguez, José A. and Suib, Steven L. and Senanayake, Sanjaya D.},
abstractNote = {Mesoporous Ni/CeO2 catalysts of variable loadings were prepared using in-situ doping and impregnation synthesis techniques. The catalysts were found to exhibit activity for the water-gas shift (WGS) reaction, particularly at temperatures above 250 °C. Structural, electronic, and surface chemical characterizations of the materials were carried out using in-situ X-ray diffraction (XRD), in-situ X-ray absorption (XANES), and in-situ infrared (DRIFTS) techniques. The effects of metal loading and preparation method on these properties were studied in order to develop a more complete understanding of the design and application of Ni-loaded mesoporous CeO2 catalysts. For WGS reaction activity, the in-situ doping method was observed to be superior, and overall activity was observed to increase with increasing metal loadings. Simple normalization of activity data to nominal nickel content revealed a trend favoring lower loadings, indicating higher activity per unit nickel. The reduction of the catalyst is observed with increasing reaction temperature (Ni2+ → Ni°, Ce4+ → Ce3+) while the active states of all catalysts were identified as a stable, partially reduced ceria fluorite lattice (Ce4+/Ce3+) with Ni2+ and Ni°. In Situ DRIFTS showed nearly identical surface chemistry for both doped and impregnated samples, likely involving an associative pathway at lower temperatures and a redox pathway at higher temperatures. Structural properties and surface chemistry were observed to depend both on metal loading and preparation method. As a result, nickel loadings as low as 1 wt% prepared by in-situ doping were found to display the most favorable metal-support interactions for the WGS reaction.},
doi = {10.1016/j.apcata.2018.08.026},
journal = {Applied Catalysis. A, General},
number = C,
volume = 567,
place = {United States},
year = {2018},
month = {8}
}

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Figures / Tables:

Figure 1 Figure 1: HRTEM images of (a) d-5NiCe and (b) i-5NiCe

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