Abstract
It is one of the important issues on environmental protection to improve the purification performance of three-way catalyst. Ceria provides a number of benefits in automotive catalysts,especially oxygen storage-the ability to store oxygen under rich-lean operating conditions. To realize the high performance of the three-way catalyst, this development focused on the heat resistance of the CeO2-ZrO2 solid solution (CZ) that possesses the oxygen storage capacity (OSC). A new concept of the OSC compound with high durability is proposed.We devised a new method of inhibiting the coagulation of the primary CZ particles by placing diffusion barrier layers made of alumina among the primary CZ particles. This material is called "ACZ". ACZ is prepared using the sol-gel or co-precipitation method. Three-way catalytic performances of the ACZ-added catalyst have been evaluated using an engine compared with those of the CZ-added catalyst. The specific surface area of ACZ was larger than that of the conventional CZ after durability test.The sintering of Pt on the ACZ-added catalyst is inhibited and the crystal size of CZ in the ACZ-added catalyst is smaller than that in the CZ-added catalyst. The dynamic OSC and the light off temperature of the ACZ-added catalyst are improved.