Characterization of surface structure and oxidation/reduction behavior of Pd-Pt/Al2O3 model catalysts
Journal article, 2016

Structural and morphological characterizations of bimetallic Pd-Pt/Al 2 O 3 model catalysts are performed using X-ray diffraction, X-ray absorption spectroscopy, transmission electron microscopy, and CO chemisorption. Further, the catalysts were studied under oxidizing and reducing conditions using both X-ray absorption spectroscopy and low-energy ion scattering spectroscopy. For the as-prepared catalysts, the existence of alloyed bimetallic Pd-Pt particles and of (tetragonal) PdO was found for the samples calcined at 800 °C. PdO is present in the form of crystals at the surface of the Pd-Pt particles or as isolated PdO crystals on the support oxide. Bimetallic Pd-Pt nanoparticles were only formed on the Pd-Pt catalysts after calcination at 800 °C. The results show that the Pd-Pt nanoparticles undergo reversible changes in surface structure composition and chemical state in response to oxidizing or reducing conditions. Under oxidizing conditions Pd segregates to the shell and oxidizes forming PdO, while under reducing conditions regions with metallic Pd and Pd-Pt alloys were observed at the surface. No bimetallic Pd-Pt nanoparticles were observed for the sample initially calcined at 500 °C, but instead isolated monometallic particles, where small Pt particles are easily oxidized under O 2 treatment. In the monometallic catalysts, the Pd is found to be completely oxidized already after calcination and to consist of metallic Pd after reductive treatment.

Author

Natalia Mihaela Martin

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Johan Nilsson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Magnus Skoglundh

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Emma Adams

Competence Centre for Catalysis (KCK)

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Xueting Wang

Competence Centre for Catalysis (KCK)

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Peter Velin

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Gudmund Smedler

Johnson Matthey AB

Agnes Raj

Johnson Matthey

David Thompsett

Johnson Matthey

Hidde H. Brongersma

Technische Universiteit Eindhoven

Thomas Grehl

ION-TOF

Giovanni Agostini

European Synchrotron Radiation Facility (ESRF)

Olivier Mathon

European Synchrotron Radiation Facility (ESRF)

Stefan Carlson

Lund University

Katarina Norén

Lund University

F. J. Martinez-Casado

Lund University

Z. Matej

Lund University

Olivier Balmes

Lund University

Per-Anders Carlsson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 120 49 28009-28020

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Subject Categories

Inorganic Chemistry

Materials Chemistry

Other Chemistry Topics

DOI

10.1021/acs.jpcc.6b09223

More information

Latest update

10/27/2018