| 摘要 |
<P>PROBLEM TO BE SOLVED: To re-disperse easily a noble metal which has grown in particle size in a stoichiometric atmosphere and prevent emission of NOx. <P>SOLUTION: An apparatus and a method for purification of exhaust gas employ a noble-metal-supported catalyst consisting of a noble metal supported in the first oxide in which the electron density of oxygen atoms is higher than that of oxygen atoms contained in γ-Al<SB>2</SB>O<SB>3</SB>and an NOx catalyst consisting of an NOx occlusion material supported in the second oxide. In normal operation, exhaust gas burned in a stoichiometric atmosphere is allowed to flow, and, after the exhaust gas atmosphere is converted to a lean atmosphere by driving a leanness imparting means, the atmosphere is switched to a rich atmosphere. Even when growing in particle size in a stoichiometric atmosphere, the grown noble metal is re-dispersed by switching of the exhaust gas to a lean atmosphere. In a lean atmosphere, NOx is occluded by the NOx occlusion material, and, after the stoichiometric atmosphere is switched to a rich atmosphere, NOx occluded in the NOx occlusion material is emitted and purified through reduction. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
