Carbon in palladium catalysts: A metastable carbide

Autor(en)

Nicola Seriani, Florian Mittendorfer, Georg Kresse

Abstrakt

The catalytic activity of palladium toward selective hydrogenation of hydrocarbons depends on the partial pressure of hydrogen. It has been suggested that the reaction proceeds selectively toward partial hydrogenation only when a carbon-rich film is present at the metal surface. On the basis of first-principles simulations, we show that carbon can dissolve into the metal because graphite formation is delayed by the large critical nucleus necessary for graphite nucleation. A bulk carbide Pd6C with a hexagonal six-layer fcc-like supercell forms. The structure is characterized by core level shifts of 0.66-0.70 eV in the core states of Pd, in agreement with experimental x-ray photoemission spectra. Moreover, this phase traps bulk-dissolved hydrogen, suppressing the total hydrogenation reaction channel and fostering partial hydrogenation.

Organisation(en)

Computergestützte Materialphysik

Journal

Journal of Chemical Physics

Band

132

Anzahl der Seiten

8

ISSN

0021-9606

DOI

https://doi.org/10.1063/1.3290813

Publikationsdatum

2010

Peer-reviewed

Ja

ÖFOS 2012

103009 Festkörperphysik, 103015 Kondensierte Materie, 103025 Quantenmechanik, 103036 Theoretische Physik

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/ac1e7c45-0385-46ac-8b43-156cf1f2ecc2