Narrow pore size distribution aluminum titanate body and method for making same

Abstract

This invention relates to an aluminum titanate body having a narrow pore size distribution as characterized by the relation (d 50 −d 10 )/d 50 being less than 0.50 corresponding to a high degree of interconnected porosity. The body also preferably exhibits a low coefficient of thermal expansion of less than 15×10 −7 C −1 , high porosity of at least 38% by volume, and at least 0.10% by weight metal oxide, the metal being either yttrium, calcium, bismuth, a lanthanide metal or combinations of thereof. MOR is preferably at least 450 psi. Median pore diameter is preferably at least 8 microns. The inventive ceramic body is particularly useful as a wall-flow filter for a diesel exhaust. A method of fabrication is provided where the sintering temperature is preferably between 1375°-1550° C.

1 . A diesel exhaust particulate filter, comprising: 
 a phase of aluminum titanate and a narrow pore size distribution as characterized by the relation (d 50 −d 10 )/d 50  being less than 0.50.    
   
   
       2 . The particulate filter of  claim 1  further comprising (d 50 −d 10 )/d 50  being less than 0.35.  
   
   
       3 . The particulate filter of  claim 1  further comprising (d 50 −d 10 )/d 50  being less than 0.25.  
   
   
       4 . The particulate filter of  claim 1  further comprising (d 50 −d 10 )/d 50  being 0.23 or less.  
   
   
       5 . The particulate filter of  claim 1  wherein the relation (d 50 −d 10 )/d 50  is less than 0.50 and greater than 0.18.  
   
   
       6 . The particulate filter of  claim 1  further comprising a phase of mullite.  
   
   
       7 . The particulate filter of  claim 1  further exhibiting a coefficient of thermal expansion (RT−1000° C.) less than 15×10 −7  C −1 .  
   
   
       8 . The particulate filter of  claim 1  further exhibiting a coefficient of thermal expansion (RT−1000° C.) not greater than 10×10 −7  C −1 .  
   
   
       9 . The particulate filter of  claim 1  further exhibiting a porosity of at least 38% by volume.  
   
   
       10 . The particulate filter of  claim 1  further exhibiting a porosity of between 45-60% by volume.  
   
   
       11 . The particulate filter of  claim 1  further exhibiting a median pore diameter of at least 8 microns.  
   
   
       12 . The particulate filter of  claim 11  further exhibiting a median pore diameter of between 10-20 microns.  
   
   
       13 . The particulate filter of  claim 1  further exhibiting a modulus of rupture (MOR) using the four point method on a cylindrical rod, of at least 450 psi.  
   
   
       14 . The particulate filter of  claim 1  further exhibiting modulus of rupture (MOR) using the four point method on a cylindrical rod, of at least 500 psi.  
   
   
       15 . The particulate filter of  claim 1  further exhibiting modulus of rupture (MOR) using the four point method on a cylindrical rod, of at least 600 psi.  
   
   
       16 . The particulate filter of  claim 1  further exhibiting modulus of rupture (MOR) using the four point method on a cylindrical rod, of at least 700 psi.  
   
   
       17 . The particulate filter of  claim 1  further exhibiting a set of properties including a coefficient of thermal expansion (RT−1000° C.) less than 10×10 −7  C −1 , a porosity of between 45-60% by volume, and a median pore diameter of between 10-20 microns.  
   
   
       18 . The ceramic body of  claim 17  further comprising a narrow pore size distribution as characterized by the relation (d 50 -d 10 )/d 50  being less than 0.35.  
   
   
       19 . The particulate filter of  claim 1  further comprising a plugged, wall-flow honeycomb body having a plurality of parallel plugged cell channels traversing the body from a frontal inlet end to an outlet end thereof.  
   
   
       20 . A honeycomb ceramic body, comprising: 
 a phase of aluminum titanate and a narrow pore size distribution as characterized by the relation (d 50 −d 10 )/d 50  being less than 0.5, and    a coefficient of thermal expansion (RT−1000° C.) less than 15×10 −7  C −1 .    
   
   
       21 . The honeycomb ceramic body of  claim 20  further comprising a porosity of greater than 38% by volume.  
   
   
       22 . The honeycomb ceramic body of  claim 20  further comprising a porosity of between 45-60% by volume.  
   
   
       23 . The honeycomb ceramic body of  claim 20  further comprising a median pore diameter of between 10-20 microns.  
   
   
       24 . The honeycomb ceramic body of  claim 1  further exhibiting a coefficient of thermal expansion (RT−1000° C.) not greater than 10×10 −7  C −1 .