Method of depleting nitrous oxide in exhaust gas after-treatment for lean-burn engines
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B01D-053/94
F01N-003/10
F01N-003/20
출원번호
US-0639424
(2011-04-05)
등록번호
US-8512658
(2013-08-20)
우선권정보
DE-10 2010 014 468 (2010-04-09)
국제출원번호
PCT/EP2011/001678
(2011-04-05)
§371/§102 date
20121004
(20121004)
국제공개번호
WO2011/124357
(2011-10-13)
발명자
/ 주소
Eckhoff, Stephan
Adam, Frank
Lammarck, Christian
출원인 / 주소
Umicore AG & Co. KG
대리인 / 주소
Smith, Gambrell & Russell, LLP
인용정보
피인용 횟수 :
5인용 특허 :
19
초록▼
The present invention relates to a method for exhaust gas after-treatment for essentially lean-burn internal combustion engines and also a corresponding advantageous exhaust gas after-treatment system. In particular, the present invention relates to reducing the proportion of the greenhouse gas N20
The present invention relates to a method for exhaust gas after-treatment for essentially lean-burn internal combustion engines and also a corresponding advantageous exhaust gas after-treatment system. In particular, the present invention relates to reducing the proportion of the greenhouse gas N20 in the total exhaust gas from a corresponding internal combustion system using at least one NOx storage catalyst as exhaust gas purification element. The objective of the invention is to operate the N20 depletion catalyst located downstream of the NOx storage catalyst under lambda=1 conditions when the N20 formed by the NOx storage catalyst reaches the N20 depletion catalyst.
대표청구항▼
1. A method of depleting harmful exhaust gases from a lean-burn internal combustion engine using an exhaust gas after-treatment system having a first NOx storage catalyst in an upstream position followed by an N2O depletion catalyst, which comprises the steps: a) passing a lean-burn exhaust gas over
1. A method of depleting harmful exhaust gases from a lean-burn internal combustion engine using an exhaust gas after-treatment system having a first NOx storage catalyst in an upstream position followed by an N2O depletion catalyst, which comprises the steps: a) passing a lean-burn exhaust gas over the NOx storage catalyst during normal operation;b) feeding an exhaust gas having λ≦1 to the N2O depletion catalyst shortly before or simultaneously with the initiation of step c);c) passing an exhaust gas mixture having λ≦1 over the NOx storage catalyst until the latter is sufficiently regenerated;d) establishing normal operation. 2. The method as claimed in claim 1, wherein the N2O depletion catalyst is a catalyst selected from the group consisting of a three-way catalyst, an NOx depletion catalyst, an NOx storage catalyst and an oxidation catalyst. 3. The method as claimed in claim 1, wherein step b) is initiated about 0.1-15 sec before initiation of step c). 4. The method as claimed in claim 1, wherein the provision of the exhaust gas mixture having λ≦1 in step b) is effected by means of a regulated bypass line for the exhaust gas around the NOx storage catalyst. 5. The method as claimed in claim 1, wherein the provision of the exhaust gas mixture having λ≦1 in step b) is effected by means of a secondary reducing agent injection into the exhaust gas between the NOx storage catalyst and the N2O depletion catalyst. 6. The method as claimed in claim 4, wherein step b) continues only until sufficient exhaust gas having λ≦1 is present upstream of the N2O depletion catalyst for N2O introduced step c) to be virtually completely reduced. 7. The method as claimed in claim 1, wherein the provision of the exhaust gas mixture having λ≦1 in step b) is, in the case of an engine comprising two rows of cylinders and having two separate exhaust gas trains each having an NOx storage catalyst, effected by combining the exhaust gas trains downstream of the NOx storage catalyst and upstream of the N2O depletion catalyst located in the common exhaust gas train and regulating the primary exhaust gas emissions for regeneration of the respective NOx storage catalyst as follows: i) setting the exhaust gas mixture in the first exhaust gas train to a λ of about 1.005-1.20;ii) setting the exhaust gas mixture in the second exhaust gas train to a λ of ≦1, so that a λ of ≦1 results in the total exhaust gas upstream of the N2O depletion catalyst;iii) maintaining the setting under i) and ii) until the NOx storage catalyst in the second exhaust gas train has been sufficiently regenerated;iv) adjusting the exhaust gas mixture in the second exhaust gas train to a λ of about 1-1.25;v) setting the exhaust gas mixture in the first exhaust gas train to a λ of ≦1, so that a λ of ≦1 results in the total exhaust gas upstream of the N2O depletion catalyst;vi) maintaining the setting under iv) and v) until the NOx storage catalyst in the first exhaust gas train is sufficiently regenerated. 8. The method as claimed in claim 1, wherein an oxidation catalyst close to the engine, a three-way catalyst close to the engine or a further NOx storage catalyst is present upstream of the NOx storage catalyst. 9. The method as claimed in claim 1, wherein the regulation of the exhaust gas system is carried out by means of sensors selected from the group consisting of lambda sensors, NOx sensors and temperature sensors or partially or exclusively by means of data stored in the ECU. 10. The method as claimed in claim 1, wherein the N2O depletion catalyst is present as a coating on a particle filter. 11. The method as claimed in claim 1, wherein the N2O depletion catalyst is heated when the temperature is below its light-off temperature. 12. An exhaust gas system for operating a method as claimed claim 1, which has an NOx storage catalyst, a regulated bypass around the NOx storage catalyst and, downstream thereof, an N2O depletion catalyst. 13. The exhaust gas system as claimed in claim 12, wherein the N2O depletion catalyst is a catalyst selected from the group consisting of a three-way catalyst, an NOx reduction catalyst, an NOx storage catalyst and an oxidation catalyst. 14. The exhaust gas system as claimed in claim 12, wherein an oxidation catalyst close to the engine, a three-way catalyst close to the engine or a further NOx storage catalyst is present upstream of the NOx storage catalyst. 15. The exhaust gas system as claimed in claim 12, wherein the N2O depletion catalyst is present as a coating on a particle filter. 16. The exhaust gas system as claimed in claim 12, wherein the regulation of the exhaust gas system is carried out by means of sensors selected from the group consisting of lambda sensors, NOx sensors and temperature sensors or partially or exclusively by means of data stored in the ECU. 17. The exhaust gas system as claimed in claim 12, wherein the N2O depletion catalyst is heatable.
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이 특허에 인용된 특허 (19)
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Ruwisch, Lutz Marc; G?bel, Ulrich; Theis, Juliane; Domesle, Rainer, Catalyst for lowering the amount of nitrogen oxides in the exhaust gas from lean burn engines.
Kakwani,Ramesh M.; Voss,Kenneth C.; Patchett,Joseph A.; Grimston,Karl R., Exhaust system for enhanced reduction of nitrogen oxides and particulates from diesel engines.
Lindner, Dieter; Mussmann, Lothar; Votsmeier, Martin; Lox, Egbert; Kreuzer, Thomas, Exhaust-gas purification catalyst to be used close to the engine and process for its production.
Gobel, Ulrich; Ruwisch, Lutz Marc; Kiessling, Ralph; Foerster, Martin, Method for producing a nitrogen oxide storage material and a storage material made with it.
Hoffman, Michael; Klein, Harald; Kreuzer, Thomas, Process for regenerating the catalytic activity of a catalyst that is located in the exhaust gas line of a diesel engine and that has at least one oxidizing function.
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