Emissions reduction system
AssigneeFord Global Technologies, LLC
InventorsJoseph Robert Theis, Christine Kay Lambert, Douglas Allen Dobson
Life of this patent
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Abstract
An exhaust system for a diesel engine is disclosed. The exhaust system may include a diesel oxidation catalyst (DOC) configured to receive exhaust gases from the engine and oxidize hydrocarbons in the exhaust gases and a passive NOx adsorber (PNA) downstream from the DOC and configured to store NOx from the exhaust gases at temperatures up to 150° C. A selective catalytic reduction (SCR) system may be downstream from the PNA and configured to reduce NOx in the exhaust gases. The PNA may be configured to release the stored NOx at temperatures above 200° C. The DOC upstream of the PNA may reduce the amount of N2O that is generated by the PNA by oxidizing hydrocarbons before they reach the PNA.
Claims17
A diesel engine exhaust system, comprising:
- a diesel oxidation catalyst (DOC) brick configured to receive exhaust gases from a diesel engine and oxidize hydrocarbons therein;
- a passive NOx adsorber (PNA) brick separate and downstream from the DOC brick and configured to store NOx from the exhaust gases up to 150° C.;
- and
- a selective catalytic reduction (SCR) system downstream from the PNA brick and configured to reduce NOx in the exhaust gases;
- wherein the PNA brick includes palladium and platinum and has a palladium to platinum content of at least 3:1.
A process, comprising:
- introducing a first exhaust gas (FEG) from a diesel engine to a diesel oxidation catalyst (DOC) front-brick to generate a second exhaust gas (SEG);
- introducing the SEG to a passive NOx adsorber (PNA) rear-brick downstream from the DOC front-brick to generate a third exhaust gas (TEG), the PNA rear-brick storing NOx from the SEG up to 150° C.;
- and
- introducing the TEG to a NOx reduction system from the PNA rear-brick;
- wherein throughout a first 2,000 seconds after starting the diesel engine, an output exhaust gas (OEG) from the NOx reduction system includes less than 10 ppm of N2O.
An exhaust system for treating exhaust gases from a diesel engine, comprising:
- a passive NOx adsorber (PNA) layer disposed on a substrate and configured to store NOx from the exhaust gases at temperatures up to 150° C.;
- a diesel oxidation catalyst (DOC) layer disposed over the PNA layer and configured to contact the exhaust gases before they contact the PNA layer and to oxidize hydrocarbons in the exhaust gases;
- and
- a selective catalytic reduction (SCR) system downstream from the PNA and DOC layers and configured to reduce NOx in the exhaust gases;
- wherein the PNA layer and the DOC layer each include palladium and platinum and have a palladium to platinum content of at least 3:1.
Dependencies are inferred from the claim text.