Catalytic Converter Configuration and Method for Desulfurizing a NOx Storage Catalytic Converter

Abstract

A catalytic converter configuration for an internal combustion engine that is capable of running lean has an exhaust gas duct and a NO x storage catalytic converter arranged in the exhaust gas duct. A novel method allows desulfurizing the NO x storage catalytic converter. An H 2 S storage catalytic converter is provided. This catalytic converter is capable of storing hydrogen sulfide under a rich or stoichiometric exhaust gas atmosphere with lambda≦1 and oxidizing hydrogen sulfide under a lean exhaust gas atmosphere with lambda>1.

1 . A catalytic converter configuration for an internal combustion engine that is capable of running lean, comprising:
 an exhaust gas duct connected with the internal combustion engine;   a NO x  storage catalytic converter disposed in said exhaust gas duct; and   an H 2 S storage catalytic converter configured to store hydrogen sulfide under a rich or stoichiometric exhaust gas atmosphere with lambda≦1 and to release the hydrogen sulfide under a lean exhaust gas atmosphere with lambda>1.   
   
   
       2 . The catalytic converter configuration according to  claim 1 , wherein said H 2 S storage catalytic converter is disposed downstream and at a spacing distance from said NO x  storage catalytic converter. 
   
   
       3 . The catalytic converter configuration according to  claim 1 , wherein said H 2 S storage catalytic converter is disposed downstream and adjoining said NO x  storage catalytic converter. 
   
   
       4 . The catalytic converter configuration according to  claim 1 , wherein said H 2 S storage catalytic converter is integrated in said NO x  storage catalytic converter. 
   
   
       5 . The catalytic converter configuration according to  claim 1 , wherein said H 2 S storage catalytic converter contains at least one metal component suitable for binding H 2 S as a metal sulfide under a rich or stoichiometric exhaust gas atmosphere with lambda≦1. 
   
   
       6 . The catalytic converter configuration according to  claim 5 , wherein said metal component includes at least one metal of subgroups I, II and/or VIII of the table of elements. 
   
   
       7 . The catalytic converter configuration according to  claim 5 , wherein said metal component includes at least one component selected from the group consisting of Ag, Zn, Cd, Fe, Co, and Ni. 
   
   
       8 . The catalytic converter configuration according to  claim 5 , wherein a specific loading of said H 2 S catalytic converter with said at least one metal component amounts to at least 0.2 grams per liter. 
   
   
       9 . The catalytic converter configuration according to  claim 5 , wherein a specific loading of said H 2 S catalytic converter with said at least one metal component amounts to at least 0.5 grams per liter. 
   
   
       10 . The catalytic converter configuration according to  claim 1 , wherein said H 2 S storage catalytic converter additionally has an oxidation catalytic component or a three-way catalytic component. 
   
   
       11 . The catalytic converter configuration according to  claim 5 , wherein said H 2 S storage catalytic converter contains at least one noble metal component. 
   
   
       12 . The catalytic converter configuration according to  claim 11 , wherein said noble metal component is selected from the group consisting of platinum, palladium, and rhodium. 
   
   
       13 . The catalytic converter configuration according to  claim 1 , which further comprises a component for storing oxygen disposed downstream of said NO x  storage catalytic converter and/or of said H 2 S storage catalytic converter. 
   
   
       14 . The catalytic converter configuration according to  claim 1 , which comprises an oxygen-sensitive gas sensor disposed downstream of said NO x  storage catalytic converter and/or of said H 2 S storage catalytic converter. 
   
   
       15 . The catalytic converter configuration according to  claim 14 , wherein said oxygen-sensitive gas sensor is a lambda probe or a NO x  sensor. 
   
   
       16 . A method of desulfurizing a NO x  storage catalytic converter disposed in an exhaust gas duct of an internal combustion engine that is capable of running lean, which comprises:
 exposing the NO x  storage catalytic converter at least temporarily to a rich or stoichiometric exhaust gas atmosphere with lambda≦1 at a desulfurization temperature of the NO x  storage catalytic converter; and   storing hydrogen sulfide released from the NO x  storage catalytic converter in an H 2 S storage catalytic converter; and   releasing the hydrogen sulfide in a lean exhaust gas atmosphere with lambda>1.   
   
   
       17 . The method according to  claim 16 , which comprises, during desulfurization, alternately exposing the NO x  storage catalytic converter to rich intervals with a rich or stoichiometric exhaust gas atmosphere with lambda≦1 and in lean intervals to a lean exhaust gas atmosphere with lambda>1. 
   
   
       18 . The method according to  claim 16 , which comprises regenerating the H 2 S storage catalytic converter by an oxidation product of H 2 S. 
   
   
       19 . The method according to  claim 16 , which comprises regenerating the H 2 S storage catalytic converter by regeneration of SO 2  by exposure of the H2S storage catalytic converter to a lean exhaust gas atmosphere and a minimum temperature.