Exhaust purifier

Abstract

This exhaust gas purification system offers excellent purification performance for NH3, as well as for other components such as HC. [Solution] The exhaust gas purification device 10 is arranged in the exhaust passage 30 of the engine and comprises a first catalyst 33 including a three-way catalyst, a second catalyst 34 arranged downstream of the first catalyst 33 and including an NH3 adsorbent, a third catalyst 35 arranged downstream of the second catalyst 34 and including an HC adsorbent, a fourth catalyst 36 arranged downstream of the third catalyst 35 and including an oxidation catalyst and an oxygen storage and release material, and a secondary air supply device 40 that supplies secondary air between the first catalyst 33 and the second catalyst 34. The NH3 adsorbent is made of zeolite having a pore structure with fewer than 10 oxygen rings, and the HC adsorbent is made of zeolite having a pore structure with 10 or more oxygen rings.