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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”. 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 OSC and the light off temperature of the ACZ-added catalyst are improved.

The hydrocarbon adsorption volume character of zeolite was studied. Specifically, the relationship between aluminum content and zeolite hydrocarbon adsorption was investigated, as a potential hydrocarbon adsorbent for exhaust gas. The study also analyzed the relationship between hole diameter and zeolite hydrocarbon adsorption. It was found that hydrocarbon adsorption increased with decreasing aluminum content. Zeolite with a pore size approximately 0.1nm greater than the diameter of hydrocarbon molecules showed the best performance. Zeolites with two different pore sizes were mixed, and succeeded in adsorbing hydrocarbons of carbon number 3 and above. Silver (Ag) ion exchanged zeolite was also used to increase the adsorption of exhaust gas hydrocarbons, including those of carbon number 2.