| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a two-stage catalyst device with a catalyst arranged on the upstream side which supports at least Pt and Rh on a support including ceria, having improved purifying performance during acceleration while suppressing the grain growth of the Pt and the Rh and the solid solution of the Rh in the Pt. <P>SOLUTION: An upstream side catalyst 2 is arranged on the upstream side of a three-way catalyst 3, and a control device 6 controls a switching means 4 to avoid the upstream side catalyst 2 from being exposed to a lean-rich changing atmosphere. When the upstream side catalyst 2 carrying the Pt and the Rh on the support including the ceria is exposed to the lean-rich changing atmosphere, it is clear that the Rh is solid-solved in the Pt. Thus, exhaust gas of a rich atmosphere is only distributed in the upstream side catalyst 2 to suppress the solid solution of the Rh in the Pt and it is purified by the two catalysts, therefore improving purifying performance during acceleration. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
