| 摘要 |
PROBLEM TO BE SOLVED: To provide excellent purifying performance by providing a HC adsorptive/NOx adsorptive reduction catalyst for adsorbing HC and NOx when the contact oxygen-rich exhaust gas is at not higher than a specified temperature and desorbing the adsorbed HC at the specified temperature or higher. SOLUTION: This oxygen-rich exhaust gas purification system comprises a HC adsorptive/NOx adsorptive reduction catalyst set in a passage for oxygen- rich exhaust gas and a heating means for heating the catalyst. The used HC adsorptive/NOx adsorptive reduction catalyst adsorbs HC at a temperature lower than a specified temperature within a NO2 generating temperature range for advancing the reaction represented by 2NO+O2→2NO2, and releases the adsorbed HC at the specified temperature or higher. It also adsorbs NOx at a temperature lower than a specified temperature and reduces NOx at the specified temperature or higher. The HC adsorptive catalyst suitably contains zeolite such as MFI zeolite or Y zeolite, and as the NOx adsorptive reduction catalyst, a one containing a NOx reducing component such as platinum is suitably given. |
