Cooler Cluster Catalysis

Abstract

CHEMISTRY Very small metal clusters with a size of tens of atoms can be synthesized with molecular beam sources in the gas phase. However, wet chemical methods are generally needed to create the much larger metal clusters containing thousands of atoms. Large metal clusters can be bound to metal oxide supports and used as heterogeneous catalysts. Judai et al. have examined the reactivity of gas-phase Pd clusters (Pd4, Pd8, and Pd30) that were soft-landed on an MgO oxide support. The Pd4 clusters were unreactive in the classical auto-exhaust conversion reaction (CO + NO → CO2 + 1/2N2), but the larger clusters were active and showed maximal rates at 450 K for Pd8 and 420 K for Pd30. These temperatures are about 100 K less than those reported for supported Pd catalysts or metal surfaces. — PDS J. Am. Chem. Soc. 10.1021/ja039037k (2004).