Emission abatement systems and methods

Abstract

An emission abatement assembly includes a fuel reformer which supplies reformate gas to a catalyst. Exhaust gas from an internal combustion engine is advanced through the catalyst and into a downstream SCR catalyst.

1 . An emission abatement assembly comprising: 
 an ammonia-generating catalyst positioned to receive exhaust gas from an internal combustion engine,    an SCR catalyst positioned downstream of the ammonia-generating catalyst, and    a fuel reformer configured to generate a reformate gas comprising H 2 , the fuel reformer being positioned to introduce the reformate gas into the ammonia-generating catalyst.    
   
   
       2 . The emission abatement assembly of  claim 1 , wherein the fuel reformer comprises a plasma fuel reformer.  
   
   
       3 . The emission abatement assembly of  claim 1 , further comprising an oxidation catalyst positioned upstream of the ammonia-generating catalyst.  
   
   
       4 . The emission abatement assembly of  claim 1 , wherein the ammonia-generating catalyst comprises platinum.  
   
   
       5 . The emission abatement assembly of  claim 1 , wherein the ammonia-generating catalyst comprises palladium.  
   
   
       6 . The emission abatement assembly of  claim 1 , wherein: 
 the ammonia-generating catalyst is configured to utilize the reformate gas from the fuel reformer to convert NO X  to NH 3  when the temperature of the ammonia-generating catalyst is above a predetermined value, and    the ammonia-generating catalyst is configured to utilize the reformate gas from the fuel reformer to convert NO X  to N 2  when the temperature of the ammonia-generating catalyst is below the predetermined value.    
   
   
       7 . The emission abatement assembly of  claim 6 , wherein the SCR catalyst is configured to utilize NH 3  generated by the ammonia-generating catalyst to convert NO X  to N 2 .  
   
   
       8 . The emission abatement assembly of  claim 1 , wherein the SCR catalyst is configured to store NH 3 .  
   
   
       9 . The emission abatement assembly of  claim 1 , wherein the ammonia-generating catalyst is configured to store NO X .  
   
   
       10 . A method of operating an emission abatement assembly, the method comprising the steps of: 
 operating a fuel reformer to generate a reformate gas comprising H 2 ,    advancing exhaust gas from an internal combustion engine and the reformate gas through an ammonia-generating catalyst such that (i) a portion of the NO X  in the exhaust gas is converted into NH 3  when the temperature of the ammonia-generating catalyst is above a predetermined value, and (ii) a portion of the NO X  in the exhaust gas is converted to N 2  when the temperature of the ammonia-generating catalyst is below the predetermined value, and    advancing the exhaust gas exiting the ammonia-generating catalyst through an SCR catalyst.    
   
   
       11 . The method of  claim 10 , further comprising the step of converting NH 3  and NO X  into N 2  in the SCR catalyst.  
   
   
       12 . The method of  claim 10 , further comprising the step of advancing the exhaust gas and the reformate gas through an oxidation catalyst prior to being introduced into the ammonia-generating catalyst.  
   
   
       13 . The method of  claim 12 , wherein the operating step comprises operating the fuel reformer to generate a predetermined quantity of the reformate gas such that exhaust gas exiting the ammonia-generating catalyst has a predetermined ratio of NO X  and NH 3 .  
   
   
       14 . A method of operating an emission abatement assembly, the method comprising the steps of: 
 advancing exhaust gas and a reformate gas comprising H 2  from a fuel reformer into a ammonia-generating catalyst,    generating NH 3  with the ammonia-generating catalyst when the temperature of the ammonia-generating catalyst is above a predetermined value,    generating N 2  with the ammonia-generating catalyst when the temperature of the ammonia-generating catalyst is below the predetermined value, and    advancing the exhaust gas out of the ammonia-generating catalyst and through an SCR catalyst.    
   
   
       15 . The method of  claim 14 , further comprising the step of advancing the exhaust gas and the reformate gas through an oxidation catalyst prior to introduction into the ammonia-generating catalyst.  
   
   
       16 . The method of  claim 14 , further comprising the step of converting NH 3  and NO X  into N 2  with the SCR catalyst.  
   
   
       17 . An emission abatement assembly comprising: 
 an ammonia-generating catalyst positioned in a first parallel flow path,    a fuel reformer positioned to supply a reformate gas comprising H 2  to the ammonia-generating catalyst,    an oxidation catalyst positioned upstream of a point which splits an exhaust flow of an internal combustion engine into the first parallel flow path and a second parallel flow path which bypasses the first parallel flow path, and    an SCR catalyst positioned downstream of a point which recombines the first parallel flow path and the second parallel flow path.    
   
   
       18 . The assembly of  claim 17 , wherein the fuel reformer comprises a plasma fuel reformer.  
   
   
       19 . The assembly of  claim 17 , further comprising a flow diverter valve operable to divert the exhaust gas flow between the first parallel flow path and the second parallel flow path.  
   
   
       20 . A method of operating an emission abatement assembly, the method comprising the steps of: 
 advancing exhaust gas from an internal combustion engine through an oxidation catalyst,    splitting the exhaust gas downstream of the oxidation catalyst into (i) a first flow of exhaust gas which is advanced through a first parallel flow path, and (ii) a second flow of exhaust gas which is advanced through a second parallel flow path which bypasses the first flow path,    advancing the first flow of exhaust gas and a reformate gas comprising H 2  from a fuel reformer through an ammonia-generating catalyst positioned in the first parallel flow path,    recombining the first flow of exhaust gas and the second flow of exhaust gas, and    advancing the exhaust gas through an SCR catalyst subsequent to the recombining step.    
   
   
       21 . The method of  claim 20 , wherein the splitting step comprises operating a flow diverter valve to divert the exhaust gas into the first parallel flow path and the second parallel flow path.