Selective Catalytic Behavior Induced by Crystal-Phase Transformation in Well-Defined Bimetallic Pt-Sn Nanocrystals

Baraa Werghi; Liheng Wu; Amani M. Ebrahim; Miaofang Chi; Haoyang Ni; Matteo Cargnello; Simon R. Bare

doi:10.1002/smll.202207956

Selective Catalytic Behavior Induced by Crystal-Phase Transformation in Well-Defined Bimetallic Pt-Sn Nanocrystals

Baraa Werghi, Liheng Wu, Amani M. Ebrahim, Miaofang Chi, Haoyang Ni, Matteo Cargnello, Simon R. Bare

electron Microscopy and Microanalysis

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

8 Scopus citations

Abstract

The Pt-Sn bimetallic system is a much studied and commercially used catalyst for propane dehydrogenation. The traditionally prepared catalyst, however, suffers from inhomogeneity and phase separation of the active Pt–Sn phase. Colloidal chemistry offers a route for the synthesis of Pt–Sn bimetallic nanoparticles (NPs) in a systematic, well-defined, tailored fashion over conventional methods. Here, the successful synthesis of well-defined ≈2 nm Pt, PtSn, and Pt₃Sn nanocrystals with distinct crystallographic phases is reported; hexagonal close packing (hcp) PtSn and fcc Pt₃Sn show different activity and stability depending on the hydrogen-rich or poor environment in the feed. Moreover, face centred cubic (fcc) Pt₃Sn/Al₂O₃, which exhibited the highest stability compared to hcp PtSn, shows a unique phase transformation from an fcc phase to an L1₂-ordered superlattice. Contrary to PtSn, H₂ cofeeding has no effect on the Pt₃Sn deactivation rate. The results reveal structural dependency of the probe reaction, propane dehydrogenation, and provide a fundamental understanding of the structure−performance relationship on emerging bimetallic systems.

Original language	English
Article number	2207956
Journal	Small
Volume	19
Issue number	20
DOIs	https://doi.org/10.1002/smll.202207956
State	Published - May 17 2023

Funding

This work was supported by US Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemcial sciences, Geosciences, and Biosciences Division, Catalysis science program to the SUNCAT Center for Interface Science and Catalysis. Part of this work was performed at the Stanford Nano-shared Facilities (SNSF), supported by the National Science Foundation under award ECCS-2026822. Use of the Microscopy Instrumentation at the Center for Nanophase Materials Science, Oak Ridge National Laboratory is supported by the U.S. Department of Energy, Office of Science, and managed by UT-Battelle. Special thanks to Dr. An-Chih Yang and Jinwon Oh for their help with the collection of the TEM images. Use of the Stanford Synchrotron Radiation Light source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Co-ACCESS is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. A special thanks to Dr. Arun Somayaji S. Asundi for XPS data collection at Stanford facilities, and to Dr. Adam S. Hoffman and Dr. Jiyun Hong for help with operando setup at the XAS beamline. This work was supported by US Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemcial sciences, Geosciences, and Biosciences Division, Catalysis science program to the SUNCAT Center for Interface Science and Catalysis. Part of this work was performed at the Stanford Nano‐shared Facilities (SNSF), supported by the National Science Foundation under award ECCS‐2026822. Use of the Microscopy Instrumentation at the Center for Nanophase Materials Science, Oak Ridge National Laboratory is supported by the U.S. Department of Energy, Office of Science, and managed by UT‐Battelle. Special thanks to Dr. An‐Chih Yang and Jinwon Oh for their help with the collection of the TEM images. Use of the Stanford Synchrotron Radiation Light source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE‐AC02‐76SF00515. Co‐ACCESS is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. A special thanks to Dr. Arun Somayaji S. Asundi for XPS data collection at Stanford facilities, and to Dr. Adam S. Hoffman and Dr. Jiyun Hong for help with operando setup at the XAS beamline.

Funders	Funder number
National Science Foundation	ECCS‐2026822
U.S. Department of Energy	DE‐AC02‐76SF00515
Office of Science
Basic Energy Sciences
Chemical Sciences, Geosciences, and Biosciences Division
UT-Battelle	DE-AC02-76SF00515

Keywords

bimetallic alloys
dehydrogenation
dynamics
nanocrystals
operando
structure and size control

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10.1002/smll.202207956

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title = "Selective Catalytic Behavior Induced by Crystal-Phase Transformation in Well-Defined Bimetallic Pt-Sn Nanocrystals",

abstract = "The Pt-Sn bimetallic system is a much studied and commercially used catalyst for propane dehydrogenation. The traditionally prepared catalyst, however, suffers from inhomogeneity and phase separation of the active Pt–Sn phase. Colloidal chemistry offers a route for the synthesis of Pt–Sn bimetallic nanoparticles (NPs) in a systematic, well-defined, tailored fashion over conventional methods. Here, the successful synthesis of well-defined ≈2 nm Pt, PtSn, and Pt3Sn nanocrystals with distinct crystallographic phases is reported; hexagonal close packing (hcp) PtSn and fcc Pt3Sn show different activity and stability depending on the hydrogen-rich or poor environment in the feed. Moreover, face centred cubic (fcc) Pt3Sn/Al2O3, which exhibited the highest stability compared to hcp PtSn, shows a unique phase transformation from an fcc phase to an L12-ordered superlattice. Contrary to PtSn, H2 cofeeding has no effect on the Pt3Sn deactivation rate. The results reveal structural dependency of the probe reaction, propane dehydrogenation, and provide a fundamental understanding of the structure−performance relationship on emerging bimetallic systems.",

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author = "Baraa Werghi and Liheng Wu and Ebrahim, {Amani M.} and Miaofang Chi and Haoyang Ni and Matteo Cargnello and Bare, {Simon R.}",

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AU - Cargnello, Matteo

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N2 - The Pt-Sn bimetallic system is a much studied and commercially used catalyst for propane dehydrogenation. The traditionally prepared catalyst, however, suffers from inhomogeneity and phase separation of the active Pt–Sn phase. Colloidal chemistry offers a route for the synthesis of Pt–Sn bimetallic nanoparticles (NPs) in a systematic, well-defined, tailored fashion over conventional methods. Here, the successful synthesis of well-defined ≈2 nm Pt, PtSn, and Pt3Sn nanocrystals with distinct crystallographic phases is reported; hexagonal close packing (hcp) PtSn and fcc Pt3Sn show different activity and stability depending on the hydrogen-rich or poor environment in the feed. Moreover, face centred cubic (fcc) Pt3Sn/Al2O3, which exhibited the highest stability compared to hcp PtSn, shows a unique phase transformation from an fcc phase to an L12-ordered superlattice. Contrary to PtSn, H2 cofeeding has no effect on the Pt3Sn deactivation rate. The results reveal structural dependency of the probe reaction, propane dehydrogenation, and provide a fundamental understanding of the structure−performance relationship on emerging bimetallic systems.

AB - The Pt-Sn bimetallic system is a much studied and commercially used catalyst for propane dehydrogenation. The traditionally prepared catalyst, however, suffers from inhomogeneity and phase separation of the active Pt–Sn phase. Colloidal chemistry offers a route for the synthesis of Pt–Sn bimetallic nanoparticles (NPs) in a systematic, well-defined, tailored fashion over conventional methods. Here, the successful synthesis of well-defined ≈2 nm Pt, PtSn, and Pt3Sn nanocrystals with distinct crystallographic phases is reported; hexagonal close packing (hcp) PtSn and fcc Pt3Sn show different activity and stability depending on the hydrogen-rich or poor environment in the feed. Moreover, face centred cubic (fcc) Pt3Sn/Al2O3, which exhibited the highest stability compared to hcp PtSn, shows a unique phase transformation from an fcc phase to an L12-ordered superlattice. Contrary to PtSn, H2 cofeeding has no effect on the Pt3Sn deactivation rate. The results reveal structural dependency of the probe reaction, propane dehydrogenation, and provide a fundamental understanding of the structure−performance relationship on emerging bimetallic systems.

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Selective Catalytic Behavior Induced by Crystal-Phase Transformation in Well-Defined Bimetallic Pt-Sn Nanocrystals

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