Exhaust system promoting decomposition of reductants into gaseous products
AssigneeCaterpillar Inc.
InventorsHerbert DaCosta, Mark D. Veliz, Cho Y. Liang, Jinhui Sun, Timothy Gimbert, Matthew Leustek
Life of this patent
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Abstract
An engine exhaust treatment system. The treatment system includes and a reductant injector adapted to deliver a reductant composition into an exhaust stream moving along an exhaust flow path. A selective catalytic reduction device is disposed downstream from the reductant injector. The selective catalytic reduction device is adapted to reduce an amount of NOx in exhaust gases produced by an engine by reaction of the NOx with ammonia. A basic and/or amphoteric oxide contact surface is disposed along the exhaust flow path.
Claims25
An engine exhaust treatment system, comprising:
- a reductant injector adapted to deliver a reductant composition into an exhaust stream moving along an exhaust flow path defined by an exhaust conduit;
- a selective catalytic reduction device disposed downstream from the reductant injector, the selective catalytic reduction device being adapted to reduce an amount of NOx in exhaust gases produced by an engine by reaction of the NOx with ammonia;
- and
- a contact surface of a material selected from the group consisting of basic metal oxide, amphoteric metal oxide and blends thereof disposed along the exhaust flow path.
An engine exhaust treatment system, comprising:
- a reductant injector adapted to deliver a reductant composition into an exhaust stream moving along an exhaust flow path defined by an exhaust conduit;
- a reductant mixer in fluid communication with the reductant injector;
- a selective catalytic reduction device disposed downstream from the reductant injector, the selective catalytic reduction device being adapted to reduce an amount of NOx in exhaust gases produced by an engine by reaction of the NOx with ammonia;
- and
- a basic oxide coating disposed within each of the reductant mixer and the exhaust conduit.
An engine exhaust treatment system, comprising:
- a reductant injector adapted to deliver a reductant composition into an exhaust stream moving along an exhaust flow path defined by an exhaust conduit;
- a selective catalytic reduction device disposed downstream from the reductant injector, the selective catalytic reduction device being adapted to reduce an amount of NOx in exhaust gases produced by an engine by reaction of the NOx with ammonia;
- and
- a coating layer defining a contact surface disposed along the exhaust flow path, the coating layer including a first oxide-forming metal of basic or amphoteric character in combination with at least one alloy element characterized by a Gibbs free energy of oxide formation more positive than the Gibbs free energy of oxide formation of the first oxide-forming metal.
A method of reducing an amount of NOx in exhaust gases produced by an engine by treatment of the exhaust gases in an exhaust treatment system, the exhaust treatment system including a reductant injector adapted to deliver a reductant composition into an exhaust stream moving along an exhaust flow path defined by an exhaust conduit, and a selective catalytic reduction device disposed downstream from the reductant injector, the selective catalytic reduction device being adapted to reduce an amount of NOx in the exhaust gases by reaction of the NOx with ammonia, the method comprising:
- providing a contact surface of a material selected from the group consisting of basic oxide, amphoteric oxide and blends thereof disposed along the exhaust flow path upstream from the selective catalytic reduction device.
Dependencies are inferred from the claim text.