EXHAUST GAS PURIFICATION APPARATUS

摘要

An exhaust gas purification apparatus for diesel engine that is enhanced in NOx purification performance and PM purification performance. There is provided an exhaust gas purification apparatus comprising upstream catalyst (3) of straight flow structure carrying a first NOx occluding material capable of effectively occluding NOx in a low temperature region and carrying a noble metal; midstream catalyst (4) of straight flow structure carrying a second NOx occluding material capable of effectively occluding NOx in an intermediate temperature region and carrying a noble metal; and downstream catalyst (5) of wall flow structure carrying a third NOx occluding material capable of effectively occluding NOx in a high temperature region and carrying a noble metal. Enhancing of the NOx purification performance and PM purification performance can be attained as the three types of catalysts individually occlude NOx satisfactorily in correspondence to exhaust gas temperatures.