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Delivering a modifying element to metal nanoparticles via support: Pt-Ga alloying during the reduction of Pt/Mg(Al,Ga)Ox catalysts and its effects on propane dehydrogenation

Evgeniy Redekop (UGent) , Vladimir Galvita (UGent) , Hilde Poelman (UGent) , Vitaliy Bliznuk (UGent) , Christophe Detavernier (UGent) and Guy Marin (UGent)
(2014) ACS CATALYSIS. 4(6). p.1812-1824
Author
Organization
Project
IAP P7/05
Project
Methusalem-01M00409
Project
Marie Curie-301703
Project
FWO
Abstract
The alloying of Pt with Ga delivered from a hydrotalcite-like support was investigated as a strategy to produce bimetallic catalysts for propane dehydrogenation. A series of Pt/Mg(Al,Ga)O-x catalysts (2-3 wt % Pt, Ga/Pt molar ratios between 0 and 10) and a model Pt/Ga2O3 catalyst (4 wt % Pt, Ga/Pt molar ratio of 50) were characterized by means of X-ray diffraction (XRD), transmission electron microscopy, and activity measurements (873 K, W-cat/F-C3Hg,F-0 = 25 kg(cat).s.mol(-1) and P-C3Hg,P-0 = 5 kPa at a total pressure of 101.3 kPa). XRD patterns taken during temperature-programmed reduction in 5% H-2/He and isothermal reduction/oxidation cycling between 5% H-2/He and 20% O-2/N-2 at 873 K revealed dynamic alloy formation and segregation that depended upon the gas environment and Ga content. Alloying on the Pt/Mg(Al,Ga)O-x catalyst with a Ga/Pt ratio of 2 could not be observed by XRD. For a Ga/Pt ratio of 10, an alloy with a diffraction peak at 40.2 degrees was formed during the initial reduction. After subsequent reduction/oxidation treatments, this catalyst evolved toward a stable periodic cycling between pure Pt and one or more Pt-Ga alloys with characteristic peaks at 40.2 degrees and 46.5 degrees. The exact composition of the Pt-Ga alloy(s) could not be identified. On the model Pt/Ga2O3 catalyst, an alloy was formed with the same characteristic peak at 40.2 degrees as on the Ga-rich Pt/Mg(AI,Ga)O-x. In addition, another Pt-Ga alloy appeared on the Pt/Ga2O3 catalyst, which was identified as a stoichiometric PtGa phase. These alloys were formed on Pt/Ga2O3 at a lower temperature than on Pt/Mg(Al,Ga)O-x and they were stable during the reduction/oxidation cycling. Catalytic activity measurements demonstrated that the formation of Pt-Ga alloys on the Pt/Mg(Al,Ga)O-x sample with a Ga/Pt ratio of 10 and on the Pt/Ga2O3 catalyst led to pronounced enhancement of the initial selectivity toward propylene, but lower activity per exposed Pt atom.
Keywords
bimetallic catalysts, Pt-Ga, catalyst preparation methods, propane dehydrogenation, in situ XRD, ALKANE DEHYDROGENATION, ETHANE DEHYDROGENATION, NANOSTRUCTURED MATERIALS, BIMETALLIC CATALYSTS, IN-SITU, SURFACE, HYDROGENATION, CHEMISTRY, CARBON, SIZE

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Chicago
Redekop, Evgeniy, Vladimir Galvita, Hilde Poelman, Vitaliy Bliznuk, Christophe Detavernier, and Guy Marin. 2014. “Delivering a Modifying Element to Metal Nanoparticles via Support: Pt-Ga Alloying During the Reduction of Pt/Mg(Al,Ga)Ox Catalysts and Its Effects on Propane Dehydrogenation.” Acs Catalysis 4 (6): 1812–1824.
APA
Redekop, Evgeniy, Galvita, V., Poelman, H., Bliznuk, V., Detavernier, C., & Marin, G. (2014). Delivering a modifying element to metal nanoparticles via support: Pt-Ga alloying during the reduction of Pt/Mg(Al,Ga)Ox catalysts and its effects on propane dehydrogenation. ACS CATALYSIS, 4(6), 1812–1824.
Vancouver
1.
Redekop E, Galvita V, Poelman H, Bliznuk V, Detavernier C, Marin G. Delivering a modifying element to metal nanoparticles via support: Pt-Ga alloying during the reduction of Pt/Mg(Al,Ga)Ox catalysts and its effects on propane dehydrogenation. ACS CATALYSIS. 2014;4(6):1812–24.
MLA
Redekop, Evgeniy, Vladimir Galvita, Hilde Poelman, et al. “Delivering a Modifying Element to Metal Nanoparticles via Support: Pt-Ga Alloying During the Reduction of Pt/Mg(Al,Ga)Ox Catalysts and Its Effects on Propane Dehydrogenation.” ACS CATALYSIS 4.6 (2014): 1812–1824. Print.
@article{4381016,
  abstract     = {The alloying of Pt with Ga delivered from a hydrotalcite-like support was investigated as a strategy to produce bimetallic catalysts for propane dehydrogenation. A series of Pt/Mg(Al,Ga)O-x catalysts (2-3 wt \% Pt, Ga/Pt molar ratios between 0 and 10) and a model Pt/Ga2O3 catalyst (4 wt \% Pt, Ga/Pt molar ratio of 50) were characterized by means of X-ray diffraction (XRD), transmission electron microscopy, and activity measurements (873 K, W-cat/F-C3Hg,F-0 = 25 kg(cat).s.mol(-1) and P-C3Hg,P-0 = 5 kPa at a total pressure of 101.3 kPa). XRD patterns taken during temperature-programmed reduction in 5\% H-2/He and isothermal reduction/oxidation cycling between 5\% H-2/He and 20\% O-2/N-2 at 873 K revealed dynamic alloy formation and segregation that depended upon the gas environment and Ga content. Alloying on the Pt/Mg(Al,Ga)O-x catalyst with a Ga/Pt ratio of 2 could not be observed by XRD. For a Ga/Pt ratio of 10, an alloy with a diffraction peak at 40.2 degrees was formed during the initial reduction. After subsequent reduction/oxidation treatments, this catalyst evolved toward a stable periodic cycling between pure Pt and one or more Pt-Ga alloys with characteristic peaks at 40.2 degrees and 46.5 degrees. The exact composition of the Pt-Ga alloy(s) could not be identified. On the model Pt/Ga2O3 catalyst, an alloy was formed with the same characteristic peak at 40.2 degrees as on the Ga-rich Pt/Mg(AI,Ga)O-x. In addition, another Pt-Ga alloy appeared on the Pt/Ga2O3 catalyst, which was identified as a stoichiometric PtGa phase. These alloys were formed on Pt/Ga2O3 at a lower temperature than on Pt/Mg(Al,Ga)O-x and they were stable during the reduction/oxidation cycling. Catalytic activity measurements demonstrated that the formation of Pt-Ga alloys on the Pt/Mg(Al,Ga)O-x sample with a Ga/Pt ratio of 10 and on the Pt/Ga2O3 catalyst led to pronounced enhancement of the initial selectivity toward propylene, but lower activity per exposed Pt atom.},
  author       = {Redekop, Evgeniy and Galvita, Vladimir and Poelman, Hilde and Bliznuk, Vitaliy and Detavernier, Christophe and Marin, Guy},
  issn         = {2155-5435},
  journal      = {ACS CATALYSIS},
  language     = {eng},
  number       = {6},
  pages        = {1812--1824},
  title        = {Delivering a modifying element to metal nanoparticles via support: Pt-Ga alloying during the reduction of Pt/Mg(Al,Ga)Ox catalysts and its effects on propane dehydrogenation},
  url          = {http://dx.doi.org/10.1021/cs500415e},
  volume       = {4},
  year         = {2014},
}

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