Umicore Ag & Co Kg

Friedemann Rohr

Thomas Kreuzer

Egbert Lox

Stephan Eckhoff

Markus Koegel

Ulrich Goebel

Wilfried Mueller

Ruediger Hoyer

Lutz Marc Ruwisch

Ina Grisstede

Juliane Kluge

Peter Kattwinkel

Stefan D Peter

Susanne Philipp

A nitrogen oxide storage catalytic converter which is operated for a relatively long time at low exhaust-gas temperatures in the range between 120 and 250&#xb0; C. exhibits a decreasing storage capacity as a result of incomplete regeneration at said temperatures. In order to re-establish the original storage capacity of the catalytic converter which is operated in this way, two-stage regeneration is proposed, wherein the storage catalytic converter is initially partially regenerated at the low exhaust gas temperature by means of a switch from the lean mode to the rich mode, and wherein subsequently, with rich exhaust gas again, the exhaust-gas temperature of the engine is raised into a range of between 300 and 400&#xb0; C. for complete regeneration.

Method for operating a nitrogen oxide storage catalyst in a diesel engine

The present invention provides a process and a device for regeneration of a nitrogen oxide storage catalyst in the exhaust system of a diesel engine. The process comprises a first and a second regeneration strategy. The first regeneration strategy is applied when the exhaust gas temperature is above a threshold value and comprises changing the air/fuel-ratio from a lean to a rich value during a first regeneration period. The second regeneration strategy is applied when the exhaust gas temperature is below a threshold value and comprises switching the air/fuel-ratio back and forth between lean and rich air/fuel-ratios, forming a sequence of between 2 and 10 rich pulses and between 2 and 10 lean pulses during a second regeneration period.

Process for regenerating a nitrogen oxides storage catalyst

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Hanau, Germany

Friedemann Rohr