Aftertreatment System for Simultaneous Emissions Control in Stationary Rich Burn Engines

Abstract

A catalyst system may include a three-way catalyst that may receive exhaust gases from an engine and convert the exhaust gases to first converted exhaust gases. An ammonia slip catalyst may receive the first converted exhaust gases and convert the first converted exhaust gases to second converted exhaust gases. A hydrocarbon oxidation catalyst may receive the second converted exhaust gases and convert the second converted exhaust gases to third converted exhaust gases.

What is claimed is: 
     
         1 . A system comprising:
 an exhaust aftertreament system, comprising:
 a three-way catalyst that receives exhaust gases from an engine and converts the exhaust gases to first converted exhaust gases; 
 an ammonia slip catalyst that receives the first converted exhaust gases and converts the first converted exhaust gases to second converted exhaust gases; 
 a hydrocarbon oxidation catalyst that receives the second converted exhaust gases and converts the second converted exhaust gases to third converted exhaust gases; and 
 a mid-bed air injection system that injects air into the first converted exhaust gases upstream of the ammonia slip catalyst and injects air into the second converted exhaust gases upstream of the hydrocarbon oxidation catalyst. 
   
     
     
         2 . The system of  claim 1 , wherein the ammonia slip catalyst comprises a precious metal loading and a zeolite coating. 
     
     
         3 . The system of  claim 2 , wherein the precious metal loading comprises at least one of platinum or palladium. 
     
     
         4 . The system of  claim 1 , wherein the ammonia slip catalyst converts carbon monoxide in the first converted exhaust gases to carbon dioxide. 
     
     
         5 . The system of  claim 4 , wherein the ammonia slip catalyst converts ammonia in the first converted exhaust gases to nitrogen. 
     
     
         6 . The system of  claim 1 , comprising the engine coupled to the exhaust aftertreatment system. 
     
     
         7 . The system of  claim 6 , wherein the engine comprises a rich burn internal combustion engine. 
     
     
         8 . A method comprising:
 receiving exhaust gases from an engine at a three-way catalyst;   converting, at the three-way catalyst, the exhaust gases to first converted exhaust gases;   injecting air, via a mid-bed air injection system, into the first converted exhaust gases upstream of an ammonia slip catalyst;   receiving the first converted exhaust gases at the ammonia slip catalyst;   converting, at the ammonia slip catalyst, the first converted exhaust gases to second converted exhaust gases;   injecting air, via the mid-bed air injection system, into the second converted exhaust gases upstream of the hydrocarbon oxidation catalyst;   receiving the second converted exhaust gases at the hydrocarbon oxidation catalyst; and   converting, at the hydrocarbon oxidation catalyst, the second converted exhaust gases to third converted exhaust gases.   
     
     
         9 . The method of  claim 8 , wherein the ammonia slip catalyst comprises a precious metal loading and a zeolite coating. 
     
     
         10 . The method of  claim 9 , wherein the precious metal loading comprises at least one of platinum or palladium. 
     
     
         11 . The method of  claim 8 , wherein converting, at the ammonia slip catalyst, the first converted exhaust gases to the second converted exhaust gases comprises converting carbon monoxide in the first converted exhaust gases to carbon dioxide. 
     
     
         12 . The method of  claim 8 , wherein converting, at the ammonia slip catalyst, the first converted exhaust gases to the second converted exhaust gases comprises converting ammonia in the first converted exhaust gases to nitrogen. 
     
     
         13 . The method of  claim 8 , wherein the engine comprises a rich burn internal combustion engine. 
     
     
         14 . A system comprising:
 an internal combustion engine that generates exhaust gases;   a three-way catalyst that receives the exhaust gases and converts the exhaust gases to first converted exhaust gases;   an ammonia slip catalyst that receives the first converted exhaust gases and converts the first converted exhaust gases to second converted exhaust gases;   a hydrocarbon oxidation catalyst that receives the second converted exhaust gases and converts the second converted exhaust gases to third converted exhaust gases; and   a mid-bed air injection system that injects air into the first converted exhaust gases upstream of the ammonia slip catalyst and injects air into the second converted exhaust gases upstream of the hydrocarbon oxidation catalyst.   
     
     
         15 . The system of  claim 14 , wherein the ammonia slip catalyst comprises a dual layer catalyst. 
     
     
         16 . The system of  claim 15 , wherein the ammonia slip catalyst comprises a precious metal loading and a zeolite coating. 
     
     
         17 . The system of  claim 14 , wherein the ammonia slip catalyst converts ammonia in the first converted exhaust gases to nitrogen. 
     
     
         18 . The system of  claim 14 , wherein the ammonia slip catalyst converts carbon monoxide in the first converted exhaust gases to carbon dioxide. 
     
     
         19 . The system of  claim 14 , wherein the internal combustion engine comprises a rich burn internal combustion engine. 
     
     
         20 . The system of  claim 14 , wherein the three-way catalyst comprises a first precious metal loading and the ammonia slip catalyst comprises a second precious metal loading, and the second precious metal loading is less than the first precious metal loading.