Ceria Maintains Smaller Metal Catalyst Particles by Strong Metal-Support Bonding

Abstract

Keeping Nanoparticles Small Heterogeneous catalysts that consist of small metal nanoparticles absorbed on oxide supports can deactivate over time through a process called sintering. Elevated temperatures increase the rate of diffusion of metal atoms over the support, and larger, less reactive particles grow at the expense of smaller ones. Some supports that contain reducible metals, such as cerium oxide, tend to resist sintering better than oxides such as alumina. Farmer and Campbell (p. 933 ) present an analysis of previous calorimetry data for silver nanoparticles on magnesium oxides and cerium oxide surfaces and show that nanoparticles smaller than 1000 atoms are bound much more strongly to reduced cerium oxide. The energetic driving force for creating larger particles is quite low on these surfaces and increases the lifetime of smaller particles.