Catalytically active particulate filter body and method of making

Abstract

A method is disclosed for making a catalyzed particulate filter with high clean filtration efficiency which may include applying a catalyst material to a filter body having porous filter walls, wherein filtration material comprising filtration particles are disposed on or in or both on and in porous filter walls, and the filtration material is hydrophobic while the catalyst material is applied. A catalyzed particulate filter with high clean filtration efficiency is also disclosed wherein the filter includes porous filter walls with filtration particles disposed on or in or both on and in the porous filter walls, and catalyst material disposed on or in or both on and in the porous filter walls, and wherein the catalyst material substantially does not touch the filtration particles.

What is claimed is: 
     
         1 . A filter body comprising a porous honeycomb structure comprised of porous filter walls, filtration particles supported by the porous filter walls, and catalytic material,
 wherein the structure comprises a matrix of the filter walls having an average wall thickness WT (in mils) and configured as a cellular honeycomb structure comprised of cells having a cell density of CD (cells per square inch), wherein surfaces of the filter walls define channels comprising inlet channels and outlet channels extending from an inlet end to an outlet end of the filter structure, wherein the filter body has an effective diameter D (in inches) and a length L (in inches) extending in an axial direction from the inlet end to the outlet end, wherein the filter structure comprises a first group of plugs disposed within and sealing the inlet channels at or near the outlet end and a second group of plugs disposed within and sealing the outlet channels at or near the inlet end, wherein the porous filter walls comprise opposing first and second wall surfaces,   wherein the filtration particles are disposed in the filter walls and/or on the filter walls at or near the first wall surfaces,   wherein the catalytic material is disposed in the porous filter walls and/or on the second surfaces of the porous filter walls, and the catalyst material has a bulk density (BD) in (g/m 3  of filter matrix volume),   wherein the second surfaces define the outlet channels, and   wherein the filter body has a clean filtration efficiency at 0.0 particulate loading of greater than 80% normalized to a reference filter body having a reference cell density of 300 cells per square inch and a reference average wall thickness of 8 mils.   
     
     
         2 . The filter body of  claim 1  wherein the filter body has a normalized clean filtration efficiency of greater than 85% at 0.0 particulate loading. 
     
     
         3 . The filter body of  claim 1  wherein the filter body has a normalized clean filtration efficiency of greater than 90% at 0.0 particulate loading. 
     
     
         4 . The filter body of  claim 1  wherein:
 the filter body has a catalyst loading of 150 to 200 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 92%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 2.81 kPa. 
 
     
     
         5 . The filter body of  claim 1  wherein:
 the filter body has a catalyst loading of 200 to 350 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 88%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 3.24 kPa. 
 
     
     
         6 . The filter body of  claim 1  wherein:
 the filter body has a catalyst loading of 350 to 580 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 85%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 3.60 kPa. 
 
     
     
         7 . The filter body of  claim 1  wherein:
 the walls of the matrix are configured to define 300 cells per square inch in an axial cross section of the honeycomb structure; 
 the filter walls have an average thickness of 8 mils (203 micrometers); 
 the filter body has a catalyst loading of greater than 350 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 85%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 3.24 kPa. 
 
     
     
         8 . The filter body of  claim 1  wherein:
 the filter body has a catalyst loading of 150 to 200 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 94%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 2.6 kPa. 
 
     
     
         9 . The filter body of  claim 1  wherein:
 the filter body has a catalyst loading of 200 to 350 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 90%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 3.02 kPa. 
 
     
     
         10 . The filter body of  claim 1  wherein:
 the filter body has a catalyst loading of 350 to 580 g/L of catalyst material per filter matrix volume, 
 the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 88%, and 
 the filter body exhibits a normalized clean pressure drop at 0.0 g/L of less than 3.40 kPa. 
 
     
     
         11 . The filter body of  claim 1  wherein:
 the walls of the matrix are configured to define 300 cells per square inch in an axial cross section of the honeycomb structure; 
 the filter walls have an average thickness of 8 mils (203 micrometers); 
 
       the filter body has a catalyst loading of greater than 350 g/L of catalyst material per filter matrix volume,
 the filter body exhibits a clean filtration efficiency at 0.0 g/L particulate loading of greater than 88%, and 
 the filter body exhibits a clean pressure drop at 0.0 g/L of less than 3.0 kPa. 
 
     
     
         12 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 40 to 50 g/L of filter body,
 wherein the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 92%, and 
 wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 115% of its normalized pressure drop at 0.0 g/L particulate loading. 
 
     
     
         13 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 150 to 200 g/L of filter matrix volume,
 wherein the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 92%, and 
 wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 115% of its normalized pressure drop at 0.0 g/L particulate loading. 
 
     
     
         14 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 200 to 350 g/L of filter matrix volume,
 wherein the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 88%, and 
 wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 120% of its normalized pressure drop at 0.0 g/L particulate loading. 
 
     
     
         15 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 350 to 580 g/L of filter matrix volume,
 wherein the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 85%, and 
 wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 125% of its normalized pressure drop at 0.0 g/L particulate loading. 
 
     
     
         16 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of greater than 350 g/L of filter matrix volume,
 wherein the filter body exhibits a clean filtration efficiency at 0.0 g/L particulate loading of greater than 85%, and 
 wherein the filter body exhibits a pressure drop at 0.5 g/L particulate loading which is less than 125% of its pressure drop at 0.0 g/L particulate loading. 
 
     
     
         17 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 150 to 200 g/L of filter matrix volume,
 wherein the filter body exhibits a clean filtration efficiency at 0.0 g/L particulate loading of greater than 94%, and 
 wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 110% of its normalized pressure drop at 0.0 g/L particulate loading. 
 
     
     
         18 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 200 to 350 g/L of filter matrix volume,
 wherein the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 90%, and 
 wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 115% of its normalized pressure drop at 0.0 g/L particulate loading. 
 
     
     
         19 . The filter body of  claim 1  wherein the catalytic material is present at a catalyst loading of 350 to 580 g/L of filter matrix volume,
 wherein the filter body exhibits a normalized clean filtration efficiency at 0.0 g/L particulate loading of greater than 88%, and 
 
       wherein the filter body exhibits a normalized pressure drop at 0.5 g/L particulate loading which is less than 120% of its normalized pressure drop at 0.0 g/L particulate loading. 
     
     
         20 . The filter body of  claim 1  wherein the filter body has a cell density of 300 cells per square inch and an average wall thickness of 8 mils. 
     
     
         21 . The filter body of  claim 1  wherein the catalyst material substantially does not touch the filtration particles. 
     
     
         22 . The filter body of  claim 1  wherein the catalyst material does not touch the filtration particles. 
     
     
         23 . The filter body of  claim 1  wherein at least some of the catalyst material is disposed within the walls. 
     
     
         24 . The filter body of  claim 1  wherein the filtration particles are disposed in the filter walls and/or on the filter walls at or near the first wall surfaces. 
     
     
         25 . The filter body of  claim 1  wherein the filtration particles are disposed on the filter walls at or near the first wall surfaces. 
     
     
         26 . The filter body of  claim 1  wherein the catalyst loading is disposed predominantly in-wall within the filter walls.