The Roles of Subsurface Carbon and Hydrogen in Palladium-Catalyzed Alkyne Hydrogenation
Detre Teschner,1*
János Borsodi,1,2
Attila Wootsch,2
Zsolt Révay,2
Michael Hävecker,1
Axel Knop-Gericke,1
S. David Jackson,3
Robert Schlögl1
Alkynes can be selectively hydrogenated into alkenes on solid
palladium catalysts. This process requires a strong modification
of the near-surface region of palladium, in which carbon (from
fragmented feed molecules) occupies interstitial lattice sites.
In situ x-ray photoelectron spectroscopic measurements under
reaction conditions indicated that much less carbon was dissolved
in palladium during unselective, total hydrogenation. Additional
studies of hydrogen content using in situ prompt gamma activation
analysis, which allowed us to follow the hydrogen content of
palladium during catalysis, indicated that unselective hydrogenation
proceeds on hydrogen-saturated β-hydride, whereas selective
hydrogenation was only possible after decoupling bulk properties
from the surface events. Thus, the population of subsurface
sites of palladium, by either hydrogen or carbon, governs the
hydrogenation events on the surface.
2 Institute of Isotopes, Hungarian Academy of Sciences, Post Office Box 77, Budapest H-1525, Hungary.
3 WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G128QQ, Scotland, UK.
* To whom correspondence should be addressed. E-mail: teschner{at}fhi-berlin.mpg.de
