Exhaust gas purification filter

Abstract

[Summary] [Problem] The problem addressed by the present invention lies in providing an exhaust gas purification filter which can efficiently treat particulate matter in exhaust gas. [Solution] The present invention provides an exhaust gas purification filter including a substrate comprising a plurality of porous partitions, wherein the partitions form an exhaust gas flow path, a porous catalytic layer is provided on the partitions and the catalytic layer having a thickness of 10 μm or greater is provided over at least 20% of the total length of the partitions in the lengthwise direction thereof, and the catalytic layer having a thickness of 10 μm or greater is not present on the partitions 15 mm from an outflow side.

1 . Exhaust gas purification filter including a substrate comprising a plurality of porous partitions,
 wherein the partitions form an exhaust gas flow path,   a porous catalytic layer is provided on the partitions and the catalytic layer having a thickness of 10 μm or greater is provided over at least 20% of the total length of the partitions in the lengthwise direction thereof, and   the catalytic layer having a thickness of 10 μm or greater is not present on the partitions 15 mm from an outflow side.   
     
     
         2 . Exhaust gas purification filter according to  claim 1 , wherein the application amount of catalyst component forming part of the catalytic layer varies according to the specific gravity of the catalyst component and the pore volume in the catalytic layer. 
     
     
         3 . Exhaust gas purification filter according to  claim 1  or  2 , wherein the mean diameter of the pores in the catalytic layer is between 1 and 5 μm. 
     
     
         4 . Exhaust gas purification filter according to any one of  claims 1  to  3 , wherein the void ratio of the catalytic layer is no greater than 50%. 
     
     
         5 . Exhaust gas purification filter according to any one of  claims 1  to  4 , wherein the void ratio of the partitions is between 40% and 60%. 
     
     
         6 . Exhaust gas purification filter according to any one of  claims 1  to  5 , wherein the mean diameter of the pores in the partitions is between 10 μm and 20 μm. 
     
     
         7 . Exhaust gas purification filter according to any one of  claims 1  to  6 , wherein the catalyst component may include at least one of platinum and palladium, and at least one of an alkali metal and a rare earth metal. 
     
     
         8 . Exhaust gas purification filter according to any one of  claims 1  to  7 , wherein the thickness of the catalytic layer is between 10 μm and 50 μm. 
     
     
         9 . Method for producing an exhaust gas purification filter according to any one of  claims 1  to  8 , comprising a step in which a slurry including a catalyst component and an organic pore-forming material is applied in order to form pores in a catalytic layer. 
     
     
         10 . Method for producing an exhaust gas purification filter according to  claim 9 , wherein the mean length/diameter ratio of the organic pore-forming material is 1.5 or less.