Exhaust gas purification device

Abstract

An exhaust gas purification device in which catalysts are efficiently activated and in which pressure loss caused by deposition of particulates exhausted from an internal combustion engine is suppressed. The exhaust gas purification device has a first purification section and a second purification section. The first purification section has a metal honeycomb structure where a first oxidation catalyst is carried. The second purification section is placed on the downstream side of the first purification section and has a particulate filter that carries different amounts of second oxidation catalysts on the upstream side and on the downstream side of an exhaust gas route.

1 . An exhaust gas purification device that is disposed in an exhaust passage of an internal combustion engine, and purifies exhaust gas emitted from the internal combustion engine, the device comprising:
 a first purification unit including a honeycomb structure of metal on which a first oxidation catalyst is supported; and   a second purification unit that is disposed downstream of the first purification unit and includes a particulate filter on which a second oxidation catalyst is supported so that loaded amounts at an upstream side thereof and a downstream side thereof are different.   
     
     
         2 . The exhaust gas purification device according to  claim 1 , wherein
 the honeycomb structure is retained at a retaining member, the retaining member is formed in two pieces including an inner tube and an outer tube, and   an air space layer is formed between the inner tube and the outer tube.   
     
     
         3 . The exhaust gas purification device according to  claim 1 , wherein the particulate filter contains a larger loaded amount of the second oxidation catalyst at an upstream side thereof than at a downstream side thereof. 
     
     
         4 . The exhaust gas purification device according to  claim 1 , wherein a region having a relatively larger loaded amount of the second oxidation catalyst is formed from the upstream side of the particulate filter in a region in the range of 20 to 800 of a length of the particulate filter in an axial direction. 
     
     
         5 . The exhaust gas purification device according to  claim 1 , wherein the first oxidation catalyst at least contains Pt, alumina, ceria and a zeolite. 
     
     
         6 . The exhaust gas purification device according to  claim 1 , wherein the first purification unit includes one or more of the honeycomb structure. 
     
     
         7 . The exhaust gas purification device according to  claim 1 , wherein the second oxidation catalyst at least contains Pt, Pd and alumina.