Coordinatively unsaturated Al3+ centers as binding sites for active catalyst phases of platinum on gamma-Al2O3.
In many heterogeneous catalysts, the interaction of metal particles with their oxide support can alter the electronic properties of the metal and can play a critical role in determining particle morphology and maintaining dispersion. We used a combination of ultrahigh magnetic field, solid-state magic-angle spinning nuclear magnetic resonance spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy coupled with density functional theory calculations to reveal the nature of anchoring sites of a catalytically active phase of platinum on the surface of a gamma-Al2O3 catalyst support material. The results obtained show that coordinatively unsaturated pentacoordinate Al3+ (Al3+penta) centers present on the (100) facets of the gamma-Al2O3 surface are anchoring Pt. At low loadings, the active catalytic phase is atomically dispersed on the support surface (Pt/Al3+penta = 1), whereas two-dimensional Pt rafts form at higher coverages.
Kwak
Ja Hun
JH
Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, Post Office Box 999, MSIN K8-87, Richland, WA 99352, USA. Kwak@pnl.gov
Hu
Jianzhi
J
Mei
Donghai
D
Yi
Cheol-Woo
CW
Kim
Do Heui
DH
Peden
Charles H F
CH
Allard
Lawrence F
LF
Szanyi
Janos
J