Device for clarifying exhaust gas from internal combustion engine

Abstract

An exhaust emission control system for an internal combustion engine is provided. The exhaust emission control system () includes a monolith catalyst (MC) that includes an oxygen storage agent and a noble metal-based three-way catalyst including Pd, Rh, and Pt disposed at an upstream location in the exhaust gas flow in the internal combustion engine (), and a perovskite-type double oxide having a three-way catalytic function disposed at a downstream location in the exhaust gas flow. The amount C1 of Pd carried is 0.97 g/L≦C1≦1.68 g/L, the amount C2 of Rh carried is 0.11 g/L≦C2≦0.2 g/L, the amount C3 of Pt carried is 0.06 g/L≦C3≦0.11 g/L, the amount C4 of the oxygen storage agent carried is 25 g/L≦C4≦75 g/L, and the amount C5 of the perovskite-type double oxide carried is 5 g/L≦C5≦15 g/L. It is thereby possible to provide an exhaust emission control system that can reduce the production cost by reducing the amount of noble metal-based three-way catalyst used and at the same time can maintain a high exhaust emission control rate.