Thermal stabilization of catalytic compositions for automobile exhaust treatment through rare earth modification of alumina nanoparticle support

The relationship of materials design and thermal stabilization of catalysts is discussed by focusing on a series of useful rare earth elements used in automotive catalysts. In general, automobile exhaust becomes a high-temperature gas after the engine operation. The thermal durability is very important in any case of practical usage concerning with the exhaust catalyst. The catalysis, i.e., complex reactions between gases, must be discussed about the catalytic materials subjected to such harsh heat condition. Rare earth elements, in the design of advanced catalysts, are essential to the requirement of heat-stable catalytic materials as well as other function including oxygen storage capacity. For the alumina catalytic support, the phase transition and surface modification are closely related to realize better heat-stable materials with nanometer-order particles in size. The thermal-stable alumina support and the oxygen storage capacity (OSC) of ceria and ceria-zirconia subcatalysts must be controlled by the resultant rnicrostructures where the nanoparticles are mixed and rearranged with each other after heat treatment. The materials aspect for the design of automotive catalyst is reviewed, and then the author's work on the use of rare earth elements as key technology is described. (c) 2005 Elsevier B.V. All rights reserved.