"intelligent" Pt Catalysts Studied on High-Surface-Area CaTiO3 Films

Chao Lin; Alexandre C. Foucher; Yichen Ji; Christopher D. Curran; Eric A. Stach; Steven McIntosh; Raymond J. Gorte

doi:10.1021/acscatal.9b01278

"intelligent" Pt Catalysts Studied on High-Surface-Area CaTiO₃ Films

Chao Lin, Alexandre C. Foucher, Yichen Ji, Christopher D. Curran, Eric A. Stach, Steven McIntosh, Raymond J. Gorte

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

42 Scopus citations

Abstract

CaTiO₃-supported Pt is sometimes referred to as an "Intelligent" catalyst because Pt can reversibly leave or enter the perovskite lattice following high-temperature reduction or oxidation; however, slow egress-ingress kinetics associated with large perovskite crystallites make these systems impractical. In the present work, thin films (-1 nm) of CaTiO₃ were deposited onto MgAl₂O₄ and then examined as catalyst supports for Pt and Pd. While Pd/CaTiO₃/MgAl₂O₄ showed adsorption and CO-oxidation properties that were essentially the same as Pd/MgAl₂O₄, the Pt/CaTiO₃/MgAl₂O₄ catalyst exhibited evidence for strong support interactions. Pt/CaTiO₃/MgAl₂O₄ showed high activity for CO oxidation following reduction at 1073 K, even though CO adsorption was suppressed, but the catalysts were dramatically less active after oxidation at 1073 K and reduction at 773 K. Both Pt/CaTiO₃/MgAl₂O₄ and a catalyst formed by ex-solution of CaTi_0.95Pt_0.05O₃ exhibited very low rates for toluene hydrogenation in comparison to Pt/MgAl₂O₄. Scanning transmission electron microscopy (STEM) and energy-dispersive spectroscopy (EDS) showed that the CaTiO₃ films uniformly covered the MgAl₂O₄ surface after both reduction and oxidation at 1073 K. Pt particles on reduced Pt/CaTiO₃/MgAl₂O₄ exhibited an unusual rhombohedral shape and may be flat, a further indication of strong interactions between the metal and the support. Low-energy ion scattering (LEIS) indicated that high-temperature reduction caused a restructuring of the CaTiO₃. The implications of these results for understanding catalysts formed by ex-solution of metals from a perovskite lattice are discussed.

Original language	English
Pages (from-to)	7318-7327
Number of pages	10
Journal	ACS Catalysis
Volume	9
Issue number	8
DOIs	https://doi.org/10.1021/acscatal.9b01278
State	Published - Aug 2 2019
Externally published	Yes

Funding

C.L. and R.J.G. are grateful to the Department of Energy, Office of Basic Energy Sciences, Chemical Sciences, Geosciences and Biosciences Division, Grant No. DE-FG02-13ER16380 for support of this work. Some of this work was carried out at the Singh Center for Nanotechnology, which is supported by the NSF National Nanotechnology Coordinated Infrastructure Program under grant NNCI-1542153. A.C.F. and E.A.S. acknowledge support from Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC), an Energy Frontier Research Center (EFRC) funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under award no. DE-SC0012573.

Funders	Funder number
EFRC
Energy Frontier Research Center
IMASC
Integrated Mesoscale Architectures for Sustainable Catalysis
Office of Basic Energy Sciences
National Science Foundation	NNCI-1542153
U.S. Department of Energy
Office of Science
Basic Energy Sciences
Chemical Sciences, Geosciences, and Biosciences Division

Keywords

"Intelligent" catalyst
Atomic layer deposition (ALD)
CaTiO
CO oxidation
Pd
Pt
Toluene hydrogenation

Access to Document

10.1021/acscatal.9b01278

Cite this

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title = "{"}intelligent{"} Pt Catalysts Studied on High-Surface-Area CaTiO3 Films",

abstract = "CaTiO3-supported Pt is sometimes referred to as an {"}Intelligent{"} catalyst because Pt can reversibly leave or enter the perovskite lattice following high-temperature reduction or oxidation; however, slow egress-ingress kinetics associated with large perovskite crystallites make these systems impractical. In the present work, thin films (-1 nm) of CaTiO3 were deposited onto MgAl2O4 and then examined as catalyst supports for Pt and Pd. While Pd/CaTiO3/MgAl2O4 showed adsorption and CO-oxidation properties that were essentially the same as Pd/MgAl2O4, the Pt/CaTiO3/MgAl2O4 catalyst exhibited evidence for strong support interactions. Pt/CaTiO3/MgAl2O4 showed high activity for CO oxidation following reduction at 1073 K, even though CO adsorption was suppressed, but the catalysts were dramatically less active after oxidation at 1073 K and reduction at 773 K. Both Pt/CaTiO3/MgAl2O4 and a catalyst formed by ex-solution of CaTi0.95Pt0.05O3 exhibited very low rates for toluene hydrogenation in comparison to Pt/MgAl2O4. Scanning transmission electron microscopy (STEM) and energy-dispersive spectroscopy (EDS) showed that the CaTiO3 films uniformly covered the MgAl2O4 surface after both reduction and oxidation at 1073 K. Pt particles on reduced Pt/CaTiO3/MgAl2O4 exhibited an unusual rhombohedral shape and may be flat, a further indication of strong interactions between the metal and the support. Low-energy ion scattering (LEIS) indicated that high-temperature reduction caused a restructuring of the CaTiO3. The implications of these results for understanding catalysts formed by ex-solution of metals from a perovskite lattice are discussed.",

keywords = "{"}Intelligent{"} catalyst, Atomic layer deposition (ALD), CaTiO, CO oxidation, Pd, Pt, Toluene hydrogenation",

author = "Chao Lin and Foucher, {Alexandre C.} and Yichen Ji and Curran, {Christopher D.} and Stach, {Eric A.} and Steven McIntosh and Gorte, {Raymond J.}",

note = "Publisher Copyright: {\textcopyright} 2019 American Chemical Society.",

year = "2019",

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doi = "10.1021/acscatal.9b01278",

language = "English",

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T1 - "intelligent" Pt Catalysts Studied on High-Surface-Area CaTiO3 Films

AU - Lin, Chao

AU - Foucher, Alexandre C.

AU - Ji, Yichen

AU - Curran, Christopher D.

AU - Stach, Eric A.

AU - McIntosh, Steven

AU - Gorte, Raymond J.

PY - 2019/8/2

Y1 - 2019/8/2

N2 - CaTiO3-supported Pt is sometimes referred to as an "Intelligent" catalyst because Pt can reversibly leave or enter the perovskite lattice following high-temperature reduction or oxidation; however, slow egress-ingress kinetics associated with large perovskite crystallites make these systems impractical. In the present work, thin films (-1 nm) of CaTiO3 were deposited onto MgAl2O4 and then examined as catalyst supports for Pt and Pd. While Pd/CaTiO3/MgAl2O4 showed adsorption and CO-oxidation properties that were essentially the same as Pd/MgAl2O4, the Pt/CaTiO3/MgAl2O4 catalyst exhibited evidence for strong support interactions. Pt/CaTiO3/MgAl2O4 showed high activity for CO oxidation following reduction at 1073 K, even though CO adsorption was suppressed, but the catalysts were dramatically less active after oxidation at 1073 K and reduction at 773 K. Both Pt/CaTiO3/MgAl2O4 and a catalyst formed by ex-solution of CaTi0.95Pt0.05O3 exhibited very low rates for toluene hydrogenation in comparison to Pt/MgAl2O4. Scanning transmission electron microscopy (STEM) and energy-dispersive spectroscopy (EDS) showed that the CaTiO3 films uniformly covered the MgAl2O4 surface after both reduction and oxidation at 1073 K. Pt particles on reduced Pt/CaTiO3/MgAl2O4 exhibited an unusual rhombohedral shape and may be flat, a further indication of strong interactions between the metal and the support. Low-energy ion scattering (LEIS) indicated that high-temperature reduction caused a restructuring of the CaTiO3. The implications of these results for understanding catalysts formed by ex-solution of metals from a perovskite lattice are discussed.

AB - CaTiO3-supported Pt is sometimes referred to as an "Intelligent" catalyst because Pt can reversibly leave or enter the perovskite lattice following high-temperature reduction or oxidation; however, slow egress-ingress kinetics associated with large perovskite crystallites make these systems impractical. In the present work, thin films (-1 nm) of CaTiO3 were deposited onto MgAl2O4 and then examined as catalyst supports for Pt and Pd. While Pd/CaTiO3/MgAl2O4 showed adsorption and CO-oxidation properties that were essentially the same as Pd/MgAl2O4, the Pt/CaTiO3/MgAl2O4 catalyst exhibited evidence for strong support interactions. Pt/CaTiO3/MgAl2O4 showed high activity for CO oxidation following reduction at 1073 K, even though CO adsorption was suppressed, but the catalysts were dramatically less active after oxidation at 1073 K and reduction at 773 K. Both Pt/CaTiO3/MgAl2O4 and a catalyst formed by ex-solution of CaTi0.95Pt0.05O3 exhibited very low rates for toluene hydrogenation in comparison to Pt/MgAl2O4. Scanning transmission electron microscopy (STEM) and energy-dispersive spectroscopy (EDS) showed that the CaTiO3 films uniformly covered the MgAl2O4 surface after both reduction and oxidation at 1073 K. Pt particles on reduced Pt/CaTiO3/MgAl2O4 exhibited an unusual rhombohedral shape and may be flat, a further indication of strong interactions between the metal and the support. Low-energy ion scattering (LEIS) indicated that high-temperature reduction caused a restructuring of the CaTiO3. The implications of these results for understanding catalysts formed by ex-solution of metals from a perovskite lattice are discussed.

KW - "Intelligent" catalyst

KW - Atomic layer deposition (ALD)

KW - CaTiO

KW - CO oxidation

KW - Pd

KW - Pt

KW - Toluene hydrogenation

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