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What makes Fe-modified MgAl2O4 an active catalyst support? : Insight from X-ray Raman scattering

(2020) ACS CATALYSIS. 10(12). p.6613-6622
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Abstract
Fe-modified MgAl2O4 makes a surprisingly active catalyst support, likely linked to a structural effect of the Fe incorporation. Two catalyst supports, MgAl(2)O(4 )and MgAl2O4, have been studied in fresh and reduced state to determine the effect of high-temperature H-2 reduction upon ion distribution in the lattices. To this end, an X-ray Raman scattering study has been performed, focusing on the oxygen K edge and magnesium and aluminum L-2,L-3 and iron M(2,3 )soft edges. MgAl(2)O(4 )shows a random cation distribution and only small changes occur at the Mg L-2,L-3 and Al L-2,L-3 edges upon reduction at 1073 K. The main oxygen signal does lose intensity and its simulation points to a lower O covalency and more confined state after reduction. Introducing 8.9 wt % Fe into the spinel pushes Mg towards mostly tetrahedral position in the MgAl2O4 lattice, whereas Fe and Al share the octahedral sites. Concomitant lattice distortion is observable in the O signal. Reduction of MgAl2O4 leads to enhanced distortion visible in the O and Al signals and the presence of 50% Fe2+. Both disorder and reduction lead to partial segregation of MgFeOx from the MgAl2O4 lattice. This combination of distortion and phase restructuring in the Fe-modified MgAl2O4 material facilitates the lattice oxygen mobility and hence its catalytic activity.
Keywords
X-ray Raman spectroscopy, MgFeAlO spinel structure, O K edge, catalyst support, dry reforming, ELECTRONIC-STRUCTURE, ULTRASOFT PSEUDOPOTENTIALS, CATION DISTRIBUTION, CO PRODUCTION, SPINEL, METHANE, OXIDE, TEMPERATURE, SURFACE, OXYGEN

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MLA
Longo, Alessandro, et al. “What Makes Fe-Modified MgAl2O4 an Active Catalyst Support? : Insight from X-Ray Raman Scattering.” ACS CATALYSIS, vol. 10, no. 12, 2020, pp. 6613–22, doi:10.1021/acscatal.0c00759.
APA
Longo, A., Theofanidis, S.-A., Cavallari, C., Nadadur Veeraraghavan Srinath, Hu, J., Poelman, H., … Galvita, V. (2020). What makes Fe-modified MgAl2O4 an active catalyst support? : Insight from X-ray Raman scattering. ACS CATALYSIS, 10(12), 6613–6622. https://doi.org/10.1021/acscatal.0c00759
Chicago author-date
Longo, Alessandro, Stavros-Alexandros Theofanidis, Chiara Cavallari, Nadadur Veeraraghavan Srinath, Jiawei Hu, Hilde Poelman, Maarten Sabbe, Christoph J. Sahle, Guy Marin, and Vladimir Galvita. 2020. “What Makes Fe-Modified MgAl2O4 an Active Catalyst Support? : Insight from X-Ray Raman Scattering.” ACS CATALYSIS 10 (12): 6613–22. https://doi.org/10.1021/acscatal.0c00759.
Chicago author-date (all authors)
Longo, Alessandro, Stavros-Alexandros Theofanidis, Chiara Cavallari, Nadadur Veeraraghavan Srinath, Jiawei Hu, Hilde Poelman, Maarten Sabbe, Christoph J. Sahle, Guy Marin, and Vladimir Galvita. 2020. “What Makes Fe-Modified MgAl2O4 an Active Catalyst Support? : Insight from X-Ray Raman Scattering.” ACS CATALYSIS 10 (12): 6613–6622. doi:10.1021/acscatal.0c00759.
Vancouver
1.
Longo A, Theofanidis S-A, Cavallari C, Nadadur Veeraraghavan Srinath, Hu J, Poelman H, et al. What makes Fe-modified MgAl2O4 an active catalyst support? : Insight from X-ray Raman scattering. ACS CATALYSIS. 2020;10(12):6613–22.
IEEE
[1]
A. Longo et al., “What makes Fe-modified MgAl2O4 an active catalyst support? : Insight from X-ray Raman scattering,” ACS CATALYSIS, vol. 10, no. 12, pp. 6613–6622, 2020.
@article{8664029,
  abstract     = {{Fe-modified MgAl2O4 makes a surprisingly active catalyst support, likely linked to a structural effect of the Fe incorporation. Two catalyst supports, MgAl(2)O(4 )and MgAl2O4, have been studied in fresh and reduced state to determine the effect of high-temperature H-2 reduction upon ion distribution in the lattices. To this end, an X-ray Raman scattering study has been performed, focusing on the oxygen K edge and magnesium and aluminum L-2,L-3 and iron M(2,3 )soft edges. MgAl(2)O(4 )shows a random cation distribution and only small changes occur at the Mg L-2,L-3 and Al L-2,L-3 edges upon reduction at 1073 K. The main oxygen signal does lose intensity and its simulation points to a lower O covalency and more confined state after reduction. Introducing 8.9 wt % Fe into the spinel pushes Mg towards mostly tetrahedral position in the MgAl2O4 lattice, whereas Fe and Al share the octahedral sites. Concomitant lattice distortion is observable in the O signal. Reduction of MgAl2O4 leads to enhanced distortion visible in the O and Al signals and the presence of 50% Fe2+. Both disorder and reduction lead to partial segregation of MgFeOx from the MgAl2O4 lattice. This combination of distortion and phase restructuring in the Fe-modified MgAl2O4 material facilitates the lattice oxygen mobility and hence its catalytic activity.}},
  author       = {{Longo, Alessandro and Theofanidis, Stavros-Alexandros and Cavallari, Chiara and Nadadur Veeraraghavan Srinath and Hu, Jiawei and Poelman, Hilde and Sabbe, Maarten and Sahle, Christoph J. and Marin, Guy and Galvita, Vladimir}},
  issn         = {{2155-5435}},
  journal      = {{ACS CATALYSIS}},
  keywords     = {{X-ray Raman spectroscopy,MgFeAlO spinel structure,O K edge,catalyst support,dry reforming,ELECTRONIC-STRUCTURE,ULTRASOFT PSEUDOPOTENTIALS,CATION DISTRIBUTION,CO PRODUCTION,SPINEL,METHANE,OXIDE,TEMPERATURE,SURFACE,OXYGEN}},
  language     = {{eng}},
  number       = {{12}},
  pages        = {{6613--6622}},
  title        = {{What makes Fe-modified MgAl2O4 an active catalyst support? : Insight from X-ray Raman scattering}},
  url          = {{http://dx.doi.org/10.1021/acscatal.0c00759}},
  volume       = {{10}},
  year         = {{2020}},
}

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