Integrated NOx and PM reduction devices for the treatment of emissions from internal combustion engines

Abstract

One concept of the inventors relates to a system and method in which a particulate filter comprises at least about 40% by weight of an NOx adsorbant. The filter can be used as both an NOx trap and a particulate filter. By constructing the filter elements using a substantial amount of NOx adsorbant, a large volume of NOx adsorbant can be incorporated into the particulate filter, which substantially reduces the volume and expense of an exhaust system that includes both a catalytic diesel particulate filter and an NOx trap having a large quantity of NOx adsorbant. In a preferred embodiment, the filter also oxidizes NO to NO 2 . In another preferred embodiment, an SCR catalyst is position downstream of the filter elements.

1 . A particulate filter, comprising: 
 a body having an entrance and an exit; and    filter elements adapted to filter particulate matter from gas flowing between the entrance and the exit; wherein    the filter elements comprise at least about 40% by weight of an NOx adsorbant.    
   
   
       2 . The particulate filter of  claim 1 , wherein the filter elements comprise at least about 60% by weight NOx adsorbant.  
   
   
       3 . The particulate filter of  claim 1 , wherein the filter elements further comprise a catalyst for the reduction of NOx.  
   
   
       4 . The particulate filter of  claim 3 , wherein the catalyst for the reduction of NOx is also effective for oxidizing NO to NO 2 .  
   
   
       5 . The particulate filter of  claim 1 , wherein the filter elements are formed by combining NOx adsorbant particles into a cohesive mass.  
   
   
       6 . The particulate filter of  claim 1 , wherein the filter elements comprise large pores formed by interstices between NOx adsorbant particles.  
   
   
       7 . The particulate filter of  claim 1 , further comprising an effective amount of an SCR catalyst.  
   
   
       8 . The particulate filter of  claim 7 , wherein the SCR catalyst is contained in a wash coat on an exit side of the filter elements.  
   
   
       9 . A power generation system comprising the particulate filter of  claim 1 .  
   
   
       10 . The power generation system of  claim 9 , further comprising a fuel reformer configured to supply reformed fuel for regenerating the NOx adsorbant.  
   
   
       11 . A vehicle comprising the power generation system of  claim 9 .  
   
   
       12 . A method of cleaning a diesel-powered vehicle's exhaust, comprising: 
 passing the exhaust through a particulate filter comprising at least about 40% by weight NOx adsorbant to substantially reduce both a particulate matter and an NOx content of the exhaust; and    intermittently regenerating the NOx adsorbant by creating a reducing atmosphere within the particulate filter;    wherein the particulate filter is mounted on the vehicle.    
   
   
       13 . The method of  claim 12 , wherein the particulate filter comprises filter elements shaped from material comprising the NOx adsorbant.  
   
   
       14 . The method of  claim 12 , wherein regenerating the NOx adsorbant comprises supplying syn gas to the particulate filter.  
   
   
       15 . The method of  claim 12 , wherein the particulate filter comprising at least about 60% by weight of the NOx adsorbant.  
   
   
       16 . The method of  claim 12 , further comprising passing the exhaust over an effective amount of an ammonia SCR catalyst.  
   
   
       17 . The method of  claim 16 , wherein the ammonia SCR catalyst is supported by the particulate filter.  
   
   
       18 . The method of  claim 17 , wherein the ammonia SCR catalyst comprises an effective amount of catalyst selected from the group consisting of TiO 2 , WO 3 , V 2 O 5 , and MoO 3  and combinations thereof.  
   
   
       19 . The method of  claim 12 , further comprising oxidizing NO to NO 2  within the filter.  
   
   
       20 . The method of  claim 16 , further comprising oxidizing NO to NO 2  within the filter.