| 摘要 |
PURPOSE:To improve the performance to purify the NOx in an oxygen-excess exhaust gas after long use. CONSTITUTION:The carbon monoxide, hydrocarbons and NOx in an oxygen- excess exhaust gas are simultaneously purified by this catalyst to purify the exhaust gas. The catalyst consists of a carrier, herein at least one kind of element selected from alkali, alkaline-earth and rare-earth metals enters into solid soln. with titania, and a noble metal catalyst deposited on the carrier. Although SOx are absorbed by the carrier, SOx are decomposed by by the carrier and liberated from the carrier in an stoichiometrically rich atmosphere at low temp., and hence the NOx are sufficiently absorbed. The absorbed NOx react with the CO, HC, etc., in the exhaust gas in the stoichiometrically rich atmosphere and are reduced to N2 and purified. By such a mechanism, the NOx absorbing performance is not deteriorated due to the accumulation of SOx after long use, and NOx are excellently purified after long use. |
