EXHAUST GAS PURIFICATION CATALYST APPARATUS USING SELECTIVE REDUCTION-TYPE CATALYST AND EXHAUST GAS

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The selective reduction-type catalyst (SROC) has a lower catalyst layer (A) and an upper catalyst layer (B) at the surface of an integral structure-type carrier (C). the lower catalyst layer (A) contains the following components (i) a noble metal component, component (ii) alumina, titania, silica, zirconia, tungsten oxide, a transition metal oxide, a rare earth oxide, and a complex oxide thereof, and component (iii) zeolite. The upper catalyst layer (B) does not substantially contain the following component (i) and contains the following component (iii). The component (i) of the lower catalyst layer (A1) of the selective reduction-type catalyst (SROC1) at the forward stage contains a platinum component of 90% by weight or more in metal equivalent. The component (i) of the lower catalyst layer (A2) of the selective reduction-type catalyst (SROC2) at the backward stage contains a palladium component of 40% or more in metal equivalent.