Method for the desulphurisation of an oxidation catalyst arranged in the exhaust line of a diesel internal combustion engine

Abstract

A process is proposed for desulfurization of an oxidation-type catalytic converter 8 mounted downstream in the exhaust gas stream of a diesel internal combustion engine 1 with the diesel internal combustion engine 1 being operated at a lambda value λ 1 of approximately 0.98 to 0.99 and an exhaust gas temperature T 1 of at least 350° C. As a result the oxidation capacity of the oxidation-type catalytic converter 8 that is reduced by sulfur is restored within a short period of time and at moderate exhaust gas temperatures so that diesel internal combustion engines may also be operated at least temporarily with sulfurous fuel.

1 . A process for desulfurization of an oxidation-type catalytic converter mounted in the exhaust gas stream of a diesel internal combustion engine, characterized in that 
 the diesel internal combustion engine ( 1 ) is operated at a lambda value λ 1  of approximately 0.98 to 0.99 and an exhaust gas temperature T 1  of at least 350° C.    
     
     
         2 . The process as claimed in  claim 1 , wherein the desulfurization is effected under a high load and at a low speed of the diesel internal combustion engine ( 1 ).  
     
     
         3 . The process as claimed in  claim 1  or  2 , wherein throttling of the intake air is effected in order to reach the lambda value λ 1  and exhaust gas temperature T 1  respectively.  
     
     
         4 . The process as claimed in one of  claims 1  to  3 , wherein speed-synchronized afterinjection is effected in order to reach the lambda value λ 1  and exhaust gas temperature T 1  respectively.  
     
     
         5 . The process as claimed in  claim 4 , wherein the speed-synchronized afterinjection occurs a maximum of 20 degrees beyond the main injection.  
     
     
         6 . The process as claimed in one of  claims 1  to  5 , wherein lowering of the boost pressure is effected in order to reach the lambda value λ 1  and exhaust gas temperature T 1  respectively.  
     
     
         7 . The process as claimed in one of  claims 1  to  6 , wherein the desulfurization is effected when a regeneration command has been issued, the regeneration command being issued as a function of the degree of sulfurization of the oxidation-type catalytic converter ( 8 ).  
     
     
         8 . The process as claimed in one of  claims 1  to  7 , wherein the degree of sulfurization of the oxidation-type catalytic converter ( 8 ) is determined as a function of the hours of operation, the fuel throughput and/or the exhaust gas temperature of the diesel internal combustion engine ( 1 ).  
     
     
         9 . The process as claimed in one of  claims 1  to  8 , wherein the time is determined while the diesel internal combustion engine ( 1 ) is in operation at a lambda value λ 1  and above an exhaust gas temperature T 1 , so that the regeneration command may be withdrawn again after a specific regeneration period has been completed.