Device for purifying exhaust gas

Patent metadata

Field	Value
Publication number	US-10376871-B2
Application number	US-201715653870-A
Country	US
Kind code	B2
Filing date	Jul 19, 2017
Priority date	Nov 16, 2016
Publication date	Aug 13, 2019
Grant date	Aug 13, 2019

Abstract

A device for purifying exhaust gas provided to purify exhaust gas in an engine, may include an exhaust line through which exhaust gas discharged from the engine passes, a NOx storage catalyst that is installed in the exhaust line to absorb a nitrogen oxide discharged from the exhaust gas, and detach an absorbed nitrogen oxide when a temperature of a catalyst is higher than a predetermined value, and a three way catalyst (TWC) arranged in rear of the NOx storage catalyst for reducing the nitrogen oxide detached from the NOx storage catalyst, wherein the NOx storage catalyst includes an LTA zeolite catalyst.

First claim

What is claimed is:

1. A device for purifying exhaust gas provided to purify exhaust gas in an engine, the device comprising:
an exhaust line through which exhaust gas discharged from the engine passes;
a nitrogen oxide (NOx) storage catalyst that is installed in the exhaust line to absorb a nitrogen oxide discharged from the exhaust gas, and detach an absorbed nitrogen oxide when a temperature of the NOx storage catalyst is higher than a predetermined value; and
a three way catalyst (TWC) arranged in rear of the NOx storage catalyst for reducing the nitrogen oxide detached from the NOx storage catalyst,
wherein the NOx storage catalyst includes a Linde-Type A (LTA) zeolite catalyst,
wherein the LTA zeolite catalyst includes a palladium (Pd), and
wherein a content of the Pd is about 0 wt % to about 3 wt % with respect to an entire weight of the LTA zeolite catalyst.

2. The device of claim 1 , further comprising:
a controller that is configured to activate an absorption of the nitrogen oxide in the NOx storage catalyst by increasing a temperature of the exhaust gas in cold start, and control the exhaust gas in a rich condition when the temperature of the NOx storage catalyst is higher than the predetermined value.

3. The device of claim 2 , wherein:
the controller controls the exhaust gas in the rich condition by using a lambda signal of a lambda sensor when the temperature of the NOx storage catalyst is higher than the predetermined value.

4. The device of claim 2 , wherein:
the controller models the temperature of the exhaust gas according to a change of an engine driving variable, and determines the temperature of the exhaust gas and the temperature of the NOx storage catalyst in consideration of a distance from an exhaust valve of the engine and a thermal capacity.

5. The device of claim 4 , wherein:
the engine driving variable includes at least one of a RPM of the engine, a fuel amount, an air amount, a lambda value of the exhaust gas, a flow rate of the exhaust gas, and an ignition timing.

6. The device of claim 2 , wherein:
the controller increases the temperature of the exhaust gas by increasing a RPM of the engine in the cold start.

7. The device of claim 1 , wherein:
the LTA zeolite catalyst further includes at least one of platinum (Pt), rhodium (Rh), iron (Fe), copper (Cu), silver (Ag), manganese (Mn), cobalt (Co) and magnesium (Mg).

8. A method for purifying an exhaust gas in an engine by a device for purifying exhaust gas, the method comprising:
measuring a temperature of the exhaust gas and a temperature of a NOx storage catalyst;
increasing the temperature of the exhaust gas to absorb a nitrogen oxide in the NOx storage catalyst; and
controlling the exhaust gas in a rich condition when the temperature of the NOx storage catalyst is higher than a predetermined value,
wherein the NOx storage catalyst includes an LTA zeolite catalyst,
wherein the LTA zeolite catalyst includes a palladium (Pd), and
wherein a content of the Pd is about 0.1 wt % to about 3 wt % with respect to an entire weight of the LTA zeolite catalyst.

9. The method of claim 8 , wherein:
the LTA zeolite catalyst further includes at least one of Pt, Rh, Fe, Ag, Mn, Co and Mg.

10. The method of claim 8 , wherein the measuring the temperature includes:
modeling the temperature of the exhaust gas according to a change of an engine driving variable, and determining the temperature of the exhaust gas and the temperature of the NOx storage catalyst in consideration of a distance from an exhaust valve of the engine and a thermal capacity.

11. The method of claim 10 , wherein:
the engine driving variable includes at least one of a RPM of the engine; a fuel amount, an air amount, a lambda value of the exhaust gas, a flow rate of the exhaust gas, and an ignition timing.

12. The method of claim 8 , wherein the increasing the temperature of the exhaust gas includes:
increasing the temperature of the exhaust gas by increasing a RPM of the engine in a cold start, and activating an absorption of the nitrogen oxide in the NOx storage catalyst.

13. The method of claim 8 , wherein:
the controlling the exhaust gas in the rich condition controls a lambda value detected from a lambda sensor to be smaller than 1, and purifies the nitrogen oxide detached from the NOx storage catalyst by a three way catalyst (TWC) arranged in rear of the NOx storage catalyst.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Nam Yoon Sang
• Lee Hyokyung

Classifications

• F01N3/035

  with catalytic reactors · CPC title

• F01N3/0842 Primary

  Nitrogen oxides · CPC title

• F01N13/009

  having two or more separate purifying devices arranged in series · CPC title

• B01J37/0246 Primary

  Coatings comprising a zeolite · CPC title

• F01N3/0871

  using means for controlling, e.g. purging, the absorbents or adsorbents · CPC title