Characterization of surface structure and oxidation/reduction behavior of Pd-Pt/Al2O3 model catalysts
Artikel i vetenskaplig tidskrift, 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.

Författare

Natalia Mihaela Martin

Kompetenscentrum katalys (KCK)

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

Johan Nilsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Magnus Skoglundh

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Emma Adams

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Xueting Wang

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Peter Velin

Kompetenscentrum katalys (KCK)

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

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

Lunds universitet

Katarina Norén

Lunds universitet

F. J. Martinez-Casado

Lunds universitet

Z. Matej

Lunds universitet

Olivier Balmes

Lunds universitet

Per-Anders Carlsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

Journal of Physical Chemistry C

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

Vol. 120 49 28009-28020

Ämneskategorier

Oorganisk kemi

Materialkemi

Annan kemi

DOI

10.1021/acs.jpcc.6b09223

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Senast uppdaterat

2018-06-11