Multifunction catalyst, for petrol engine, includes regions optimized individually in their construction, for differing engine operational states

摘要

In respect of their exhaust gas purification functions, different catalyst regions (3, 4) have constructions optimized for different operational states of the engine. Exhaust gas (6) flow is supplied to them selectively in the catalyst casing, in accordance with the operational state of the engine. The catalyst regions (3, 4) each have a different cell density, in a concentric arrangement. The inner catalyst layer has the lower cell density. The catalyst region of higher cell density is supplied with exhaust gases, irrespectively of the position of the control valve. The exhaust purification unit (1) is part of a pre-catalyst and/or a main catalyst. Cell catalyst regions (3, 4) are formed by a monolithic substrate (2) of ceramic or metal. The differing catalyst regions each have different cell cross sections.