Coordinatively Unsaturated Al3+ Centers as Binding Sites for Active Catalyst Phases of Platinum on [gamma]-Al2O3

• Published in: Science (American Association for the Advancement of Science) 2009-09, Vol.325 (5948), p.1670-1673
• Main Authors: Kwak, Ja Hun, Hu, Jianzhi, Mei, Donghai, Cheol-Woo, Yi, Do Heui Kim, Peden, Charles H F, Allard, Lawrence F, Szanyi, Janos
• Format: Article
• Language: English
• Subjects: Aluminum; Catalysis; Metals; Platinum
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1176745

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 γ-Al2O3 catalyst support material. The results obtained show that coordinatively unsaturated pentacoordinate Al3+ (Al3+penta) centers present on the (100) facets of the γ-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. [PUBLICATION ABSTRACT]