Method of depleting nitrous oxide in exhaust gas after-treatment for lean-burn engines
AssigneeUmicore AG & Co. KG
InventorsStephan Eckhoff, Frank Adam, Christian Lammarck
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Abstract
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.
Claims17
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.
Dependencies are inferred from the claim text.