Abstract
Platinum supported on alumina is an essential component of emission treatment catalysts used in transportation. Theoretical, experimental, and mechanistic aspects of platinum particles supported on a variety of supports have been extensively studied; however, available experimental information on the behavior of single vs. sub-nanometer platinum is extremely limited. To bridge the knowledge gap between single supported platinum and well-formed supported platinum nanoparticles, we have carried out synthesis, characterization, and CO and NO oxidation studies of sub-nanometer platinum supported on α-, θ-, and γ–Al2O3 and monitored changes in structure upon exposure to CO and NO oxidation conditions. We find that sub-nanometer Pt is highly effective for CO oxidation due to high platinum dispersion but is not very efficient as NO oxidation catalyst. Furthermore, sub-nanometer platinum agglomerates rapidly under CO or NO oxidation conditions to form nanoparticles.
