초록 ▼

An exhaust gas purification catalyst with improved hydrocarbon conversion is disclosed, which contains metals from the platinum group as its catalytically active components. Two superposed functional layers are applied to one support. The catalyst has a first functional layer with a mixture of a fir

An exhaust gas purification catalyst with improved hydrocarbon conversion is disclosed, which contains metals from the platinum group as its catalytically active components. Two superposed functional layers are applied to one support. The catalyst has a first functional layer with a mixture of a first catalyst with at least one zeolite and the second functional layer applied to the first functional layer which contains a mixture of a second catalyst and at least one zeolite. The zeolites exhibit a molar ratio of silicon dioxide/aluminum oxide of more than 40 and in that at least palladium and rhodium are present as the platinum group metals and are each contained separately from one another in only one of the two catalysts. The catalyst is distinguished by particularly good suppression of hydrocarbon emissions during cold-starting and exhibits particularly good long-term stability.

대표청구항 ▼

[ We claim:] [1.] An exhaust gas purification catalyst with improved hydrocarbon conversion comprising:a first functional layer, anda second functional layer,said second functional layer overlying the first functional layer,wherein the first functional layer comprises a mixture of a first catalyst c

[ We claim:] [1.] An exhaust gas purification catalyst with improved hydrocarbon conversion comprising:a first functional layer, anda second functional layer,said second functional layer overlying the first functional layer,wherein the first functional layer comprises a mixture of a first catalyst comprising palladium and a first zeolite,wherein the second functional layer comprises a mixture of a second catalyst comprising rhodium and a second zeolite,wherein the first functional layer does not contain rhodium and the second functional layer does not contain palladium andwherein the first zeolite and the second zeolite are the same or different and do not contain any catalytically active noble metal component and exhibit a molar ratio of silicon dioxide to aluminum oxide of more than 40. [14.] A method of reducing exhaust emissions from internal combustion engines comprising:passing an exhaust gas from an internal combustion engine in contact with the exhaust purification catalyst of claim 1. A method of producing the exhaust purification catalyst of claim 1 comprising:providing the first functional layer anddepositing a second functional layer overlying the first functional layer. An exhaust gas purification catalyst with improved hydrocarbon conversion comprising:a first functional layer, anda second functional layer, said second functional layer overlying the first functional layer,wherein the first functional layer comprises a mixture of a first catalyst comprising palladium and a first zeolite,wherein the second functional layer comprises a mixture of a second catalyst comprising rhodium and a second zeolite,wherein the first functional layer does not contain rhodium and the second functional layer does not contain palladium andwherein the first zeolite does not contain any catalytically active noble metal component and exhibits a molar ratio of silicon dioxide to aluminum oxide of more than 40 and the second zeolite does not contain any catalytically active noble metal component and is a Y-type zeolite exhibiting a molar ratio of silicon dioxide to aluminum oxide of more than 100. An exhaust gas purification catalyst with improved hydrocarbon conversion comprising:a first functional layer, anda second functional layer,said second functional layer overlying the first functional layer,wherein the first functional layer consists essentially of a supported palladium catalyst and a member of the group consisting of active aluminum oxide, cerium oxide, corium/zirconium oxide and zirconium oxide or mixtures thereof and optionally a supported platinum catalyst, mixed with a ZSM5 zeolite exhibiting a molar ratio of silicon dioxide to aluminum oxide of more than 40 and does not contain any catalytically active noble metal component, andwherein the second functional layer consists essentially of a supported rhodium catalyst and a member of the group consisting of active aluminum oxide, cerium oxide, cerium/zirconium oxide and zirconium oxide or mixtures thereof and optionally a supported platinum catalyst, mixed with a dealuminized Y-zeolite exhibiting a molar ratio of silicon dioxide to aluminum oxide of more than 100 and does not contain any catalytically active noble metal component. A double layer exhaust gas purification catalyst which is applied to a support and contains palladium and rhodium separated from each other in a first layer and in a second layer,wherein said first layer comprises a first catalyst containing palladium on an active aluminum oxide, and the first layer further comprises a first zeolite mixed with said first catalyst,and the second layer overlying the first layer comprises a second catalyst containing rhodium on an active aluminum oxide, and the second layer further comprises a second zeolite mixed with said second catalyst,wherein the first and second zeolites are the same or different and do not contain any catalytically active noble metal component and exhibit a molar ratio of silicon dioxide to aluminum oxide of more than 40. The double layer exhaust gas purification catalyst of claim 18, wherein the concentration of palladium and rhodium on the active aluminum oxides is from 0.1 to 10% by weight based on the total weight of the respective catalyst.