| 摘要 |
A hydrocarbon adsorbent, a catalyst for purifying an exhaust gas, and a method for purifying the exhaust gas are provided to improve the adsorbing property of the hydrocarbon adsorbent and improve the durability of the catalyst. A hydrocarbon adsorbent comprises A-type beta-zeolite and B-type beta-zeolite, wherein the A-type beta-zeolite has a SiO2/Al2O3 ratio(molar ratio) equal to or more than 10 and less than 200, and the B-type beta-zeolite has a SiO2/Al2O3 ratio(molar ratio) in a range from 200 to 1,000. A catalyst for purifying an exhaust gas comprises a lower adsorbent layer containing the hydrocarbon adsorbent, and an upper catalyst layer formed on the lower adsorbent layer. The upper catalyst laser contains a catalytically active component selected from a group consisting of platinum, rhodium, palladium, and a mixture thereof.
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