EXHAUST GAS PURIFICATION CATALYST WITH IMPROVED HYDROCARBON CONVERSION

摘要

The invention relates to an exhaust gas purification catalyst with improved hydrocarbon conversion, which contains metals from the platinum group as its catalytically active components and comprises two superposed functional layers applied to one support. The catalyst is characterised in that the first functional layer comprises a mixture of a first catalyst with at least one zeolite and the second functional layer applied to the first functional layer comprises a mixture of a second catalyst and at least one zeolite, wherein the zeolites exhibit a molar ratio of silicon dioxide/aluminium 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.