EXHAUST GAS PURIFYING CATALYST

摘要

PURPOSE:To achieve the expansion of an active temp. region and the enhancement of activity (NOx purifying ratio) by providing two upper and lower catalyst layers different in material constitution on a carrier. CONSTITUTION:The catalyst layer formed on a carrier is constituted of a two- layered structure and transition metal ion-exchange metal-containing silicate having a noble metal supported thereon is set to a lower layer to expand the active temp. region of a catalyst on a lower temp. side and transition metal ion-exchange metal-containing silicate on which metal seed having O2 spill-over effect is supported is set to an upper layer to enhance the activity of the catalyst.