Exhaust Gas Aftertreatment Installation and Method

Abstract

An exhaust gas aftertreatment installment and associated exhaust gas aftertreatment method utilizes a nitrogen oxide storage catalytic converter and an SCR catalytic converter. A particulate filter is provided upstream of the nitrogen oxide storage catalytic converter or between the latter and the SCR catalytic converter or downstream of the SCR catalytic converter. The time of regeneration operating phases of the nitrogen oxide storage catalytic converter can be determined as a function of the nitrogen oxide content of the exhaust gas downstream of the nitrogen oxide storage catalytic converter or of the SCR catalytic converter and/or as a function of the ammonia loading of the latter. Moreover, a desired ammonia generation quantity can be determined for a respective regeneration operating phase. The installation and method are adopted for use for motor vehicle internal combustion engines and other engines which are operated predominantly in lean-burn mode.

What is claimed is: 
     
         1 . An installation for aftertreatment of exhaust gas generated by a combustion device of a motor vehicle, the installation comprising:
 an NO 2  producing catalytic converter arranged in an exhaust gas line of the motor vehicle so as to receive the exhaust gas generated by the combustion device;   an SCR catalytic converter arranged in the exhaust gas line downstream of the NO 2  producing catalytic converter, wherein the SCR catalytic converter is configured to store ammonia and to reduce nitrogen oxides in the exhaust gas with the stored ammonia;   a particulate filter arranged in the exhaust gas line downstream of the NO 2  producing catalytic converter and upstream of the SCR catalytic converter,   wherein the particulate filter has a catalytic coating comprising an SCR catalyst.   
     
     
         2 . The installation according to  claim 1 , further comprising:
 an oxidation catalytic converter arranged in the exhaust gas line downstream of the SCR catalytic converter.   
     
     
         3 . The installation according to  claim 1 , further comprising:
 a reducing agent supplying device configured to feed fuel into the exhaust gas stream upstream of the NO 2  producing catalytic converter.   
     
     
         4 . The installation according to  claim 1 , wherein the exhaust gas line comprises an exhaust pipe having an air gap insulation. 
     
     
         5 . The installation according to  claim 1 , further comprising:
 an electrical heater arranged in the exhaust gas line upstream of the NO 2  producing catalytic converter.   
     
     
         6 . The installation according to  claim 1 , wherein the SCR catalyst coating of the particulate filter is similar to a coating of the SCR catalytic converter. 
     
     
         7 . The installation according to  claim 1 , wherein the combustion device is a spark ignition engine. 
     
     
         8 . A method for operating an installation for aftertreatment of exhaust gas generated by a combustion device of a motor vehicle, the method comprising:
 receiving, by an NO 2  producing catalytic converter arranged in an exhaust gas line of the motor vehicle, the exhaust gas generated by the combustion device;   receiving, by a particulate filter arranged in the exhaust gas line downstream of the NO 2  producing catalytic converter, the exhaust gas from the NO 2  producing catalytic converter, wherein the particulate filter has a catalytic coating comprising an SCR catalyst;   receiving, by an SCR catalytic converter arranged in the exhaust gas line downstream of the particulate filter, the exhaust gas from the particulate filter; and   storing ammonia and reducing nitrogen oxides in the exhaust gas with the stored ammonia by the SCR catalytic converter.   
     
     
         9 . The method according to  claim 8 , further comprising:
 receiving, by an oxidation catalytic converter arranged in the exhaust gas line downstream of the SCR catalytic converter, the exhaust gas from the SCR catalytic converter.   
     
     
         10 . The method according to  claim 8 , further comprising:
 feeding fuel, by a reducing agent supplying device, into the exhaust gas stream upstream of the NO 2  producing catalytic converter.   
     
     
         11 . The method according to  claim 8 , wherein the exhaust gas line comprises an exhaust pipe having an air gap insulation. 
     
     
         12 . The method according to  claim 8 , further comprising:
 electrically heating, by an electrical heater arranged in the exhaust gas line upstream of the NO 2  producing catalytic converter, the exhaust gas.   
     
     
         13 . The method according to  claim 8 , wherein the SCR catalyst coating of the particulate filter is similar to a coating of the SCR catalytic converter. 
     
     
         14 . The method according to  claim 8 , wherein the combustion device is a spark ignition engine.