Influence of Pd Concentration in Au-Pd Nanoparticles for the Hydrogenation of Alkynes

Alexandre C. Foucher, Hio Tong Ngan, Tanya Shirman, Amanda Filie, Kaining Duanmu, Michael Aizenberg, Robert J. Madix, Cynthia M. Friend, Joanna Aizenberg, Philippe Sautet, Eric A. Stach

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Supported Au-Pd nanoparticles with low Pd content (between 2% and 25%) are excellent catalysts for the selective hydrogenation of alkynes into alkenes, a crucial step for elimination of alkynes from the reactants for olefin polymerization. They have better selectivity at high conversions for the hydrogenation of 1-hexyne to 1-hexene compared to that of pure Pd. However, the role of Pd concentration in Au-Pd particles in maximizing the activity per gram of Pd remains elusive. This work combines scanning transmission electron microscopy (STEM) and density functional theory (DFT) to determine how Pd concentration in the dilute limit affects the activity and selectivity of Au-Pd particles for the hydrogenation of acetylene. Atomic resolution microscopy shows increased Pd segregation to the surface with increasing Pd concentration (above 9%), and DFT analysis shows that isolated Pd atoms on the Au-Pd surface are highly active for acetylene hydrogenation compared to Pd atoms adjacent to other Pd atoms. A high concentration of isolated and active Pd atoms combined with increased segregation of Pd toward the surface explains the existence of an optimum for catalytic properties. It explains the high performance of Au0.96Pd0.04 compared to Au-Pd particles with lower or higher Pd concentrations.

Original languageEnglish
Pages (from-to)22927-22938
Number of pages12
JournalACS Applied Nano Materials
Volume6
Issue number24
DOIs
StatePublished - Dec 22 2023
Externally publishedYes

Funding

This work was supported as part of the Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award #DE-SC0012573. Experiments were also carried out at the Singh Center for Nanotechnology at the University of Pennsylvania, supported by the National Science Foundation (NSF) National Nanotechnology Coordinated Infrastructure Program grant NNCI-1542153. Additional support to the Nanoscale Characterization Facility at the Singh Center has been provided by the Laboratory for Research on the Structure of Matter (MRSEC) supported by the National Science Foundation (DMR-1720530). The DFT calculations used computational and storage services associated with the Hoffman2 cluster at the UCLA Institute for Digital Research and Education (IDRE), the National Energy Research Scientific Computing Center (NERSC) of the U.S. Department of Energy, and the Bridges-2 cluster at the Pittsburgh Supercomputing Center. The authors thank Dr. George Yan for helpful discussions.

FundersFunder number
Hoffman2 cluster at the UCLA Institute for Digital Research and Education
Laboratory for Research on the Structure of Matter
National Science FoundationNNCI-1542153
National Science Foundation
U.S. Department of Energy
Office of Science
Basic Energy Sciences-SC0012573
Basic Energy Sciences
Materials Research Science and Engineering Center, Harvard UniversityDMR-1720530
Materials Research Science and Engineering Center, Harvard University
National Energy Research Scientific Computing Center
Institute for Digital Research and Education, University of California, Los Angeles

    Keywords

    • alkyne hydrogenation
    • Catalysis
    • DFT
    • microkinetic simulation
    • optimization of Pd
    • PdAu nanocatalysts
    • STEM

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