Honeycomb filter and exhaust gas purification system

Abstract

A honeycomb filter is provided comprising a honeycomb structure having a large number of through channels formed in an axial direction and partitioned by porous partition walls, each of the through channels having a first end at one end of the filter and a second end at an opposite end of the filter, wherein a first group of the through channels are plugged only at the first end, and a second group of the through channels are not plugged. A honeycomb structure is further provided having through channels with a relatively large frontal area and through channels with a relatively small frontal area, and wherein all the through channels with a relatively large frontal area are the first group, and all the through channels with a relatively small frontal area are in the second group. A honeycomb filter is also provided with a catalyst component carried on a surface of the partition walls and/or a surface of pores present in an inside of the partition walls.

1 . A honeycomb filter comprising a honeycomb structure having a large number of through channels formed in the axial direction and partitioned by porous partition walls, each of the through channels having a first end at one end of the filter and a second end at an opposite end of the filter, wherein a first group of the through channels have a relatively large open area of cell in a cross-section parallel to the end face and are plugged only at the first end, and a second group of the through channels have a relatively small open area of cell in the end face cross-section and are not plugged,
 wherein the cross-sectional areas of the through channels are substantially uniform in the axial direction.   
   
   
       2 . The honeycomb filter according to  claim 1 , wherein a catalyst component is carried on a surface of the partition walls and/or a surface of pores present in an inside of the partition walls. 
   
   
       3 . The honeycomb filter according to  claim 2 , wherein an oxidation catalyst is carried on an internal surface of pores present in a surface of the partition walls partitioning the through channels in the first group and/or on a surface of pores present in an inside of the partition walls partitioning the through channels in the first group, and wherein a reduction catalyst is carried on an internal surface of pores present in the partition walls partitioning the through channels in the second group and/or on a surface of pores present in an inside of the partition walls partitioning the through channels in the second group. 
   
   
       4 . An exhaust gas purification system comprising a honeycomb filter comprising a honeycomb structure having a large number of through channels formed in the axial direction and partitioned by porous partition walls, each of the through channels having a first end at one end of the filter and a second end at an opposite end of the filter, wherein a first group of the through channels have a relatively large open area of cell in a cross-section parallel to the end face and are plugged only at the first end, and a second group of the through channels have a relatively small open area of cell in the end face cross-section and are not plugged,
 wherein the cross-sectional areas of the through channels are substantially uniform in the axial direction.   
   
   
       5 . The exhaust gas purification system according to  claim 4 , wherein a catalyst comprising a catalyst component carried on a honeycomb structure is further installed in front of the honeycomb filter. 
   
   
       6 . The exhaust gas purification system according to  claim 4 , comprising two of the honeycomb filters arranged in series. 
   
   
       7 . An exhaust gas purification system comprising two honeycomb filters arranged in series, each honeycomb filter comprising a honeycomb structure having a large number of through channels formed in the axial direction and partitioned by porous partition walls, each of the through channels having a first end at one end of the filter and a second end at an opposite end of the filter,
 wherein a first group of the through channels have a relatively large open area of cell in a cross-section parallel to the end face and are plugged only at the first end, and a second group of the through channels have a relatively small open area of cell in the end face cross-section and are not plugged, and   wherein said two honeycomb filters are installed in such a manner that the plugged portions of the through channels of the honeycomb filter provided in a front side are located face-to-face with end portions of the through channels of which neither end is plugged of the honeycomb filter placed in a rear side, so as to make two honeycomb filters face each other, being in contact with or joined at facing ends thereof, and   the cross-sectional areas of the through channels are substantially uniform in the axial direction.   
   
   
       8 . The exhaust gas purification system according to  claim 6 , wherein said two honeycomb filters are installed in such a manner that the plugged portions of the through channels of the honeycomb filter provided in a front side are located face-to-face with end portions of the through channels of which neither end is plugged of the honeycomb filter placed in a rear side, so as to make two honeycomb filters face each other, being in contact with or joined at facing ends thereof. 
   
   
       9 . A honeycomb filter comprising a first honeycomb filter which comprises a honeycomb structure having a large number of through channels formed in the axial direction and partitioned by porous partition walls, each of the through channels having a first end at one end of the first filter and a second end at an opposite end of the first filter, wherein a first group of the through channels have a relatively large open area of cell in a cross-section parallel to the end face and are plugged only at the first end, and a second group of the through channels have a relatively small open area of cell in the end face cross-section and are not plugged; and a second honeycomb filter which comprises a honeycomb structure having a large number of through channels formed in the axial direction and partitioned by porous partition walls, each of the through channels having a first end at one end of the second filter and a second end at an opposite end of the second filter, wherein a first group of the through channels have a relatively large open area of cell in the end face cross-section and are plugged only at the first end, and a second group of the through channels have a relatively small open area of cell in the end face cross-section and are plugged only at the second end; the first and second honeycomb filters being installed in series.