Ammonia production catalyst and after treatment system

Patent metadata

Field	Value
Publication number	US-10914217-B2
Application number	US-201916263508-A
Country	US
Kind code	B2
Filing date	Jan 31, 2019
Priority date	Jan 31, 2019
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

An after treatment system is disclosed. The after treatment system may include an exhaust pipe through which an exhaust gas flows; a three-way catalyst (TWC) mounted on the exhaust pipe and purifying HC, CO, and NOx contained in the exhaust gas, an ammonia production catalyst (APC) mounted on the exhaust pipe at a downstream of the TWC, storing NOx at a lean air/fuel ratio, and generating H2, releasing the stored NOx, and generating NH3 using the released NOx and the generated H2 at a rich air/fuel ratio, and a selective catalytic reduction (SCR) catalyst mounted on the exhaust pipe at a downstream of the APC, storing the NH3 generated in the TWC and the APC, and reducing the NOx contained in the exhaust gas using the stored NH3.

First claim

What is claimed is:

1. An after treatment system comprising:
an exhaust pipe through which an exhaust gas flows;
a three-way catalyst (TWC) mounted on the exhaust pipe and purifying HC, CO, and NOx contained in the exhaust gas;
an ammonia production catalyst (APC) mounted on the exhaust pipe at a downstream of the TWC, storing NOR at a lean air/fuel ratio, and generating H 2 , releasing the stored NOR, and generating NH 3 using the released NOR and the generated H 2 at a rich air/fuel ratio; and
a selective catalytic reduction (SCR) catalyst mounted on the exhaust pipe at a downstream of the APC, storing the NH 3 generated in the TWC and the APC, and reducing the NOR contained in the exhaust gas using the stored NH 3 , wherein the APC comprises Pt, Pd and CeO 2 , wherein a weight ratio of Pt to Pd is 3:1 to 7:1, and
wherein the NH 3 production in the APC is the greatest when the weight ratio of Pt to Pd is 4:1,
wherein weight ratio of the CeO 2 to a total weight of the APC is 10-30 wt %,
wherein a ratio of H 2 concentration increase to CeO 2 increase slows down if the CeO 2 exceeds 20 wt % based on the total weight of the APC, and
wherein the NH 3 production decreases due to increase of 02 stored in the APC if the CeO 2 exceeds 30 wt % based on the total weight of the APC.

2. The after treatment system of claim 1 , further comprising a CO cleanup catalyst (CUC) mounted on the exhaust pipe at a downstream of the SCR catalyst and purifying CO contained in the exhaust gas.

3. The after treatment system of claim 2 , further comprising a particulate filter disposed between the TWC and the APC or between the APC and the SCR catalyst,
wherein the particulate filter traps particulate matter in the exhaust gas.

4. The after treatment system of claim 1 , wherein the APC comprises 0.4-0.9 wt % of Pt, 0.057-0.3 wt % of Pd, 0.03-0.1 wt % of Rh, 5.0-15.0 wt % of Ba, 10-30 wt % of CeO2, 48.7-84.513 wt % of a composite of MgO and Al 2 O 3 , and 0-5 wt % of an additive based on a total weight of the APC.

5. The after treatment system of claim 4 , wherein the additive comprises at least one of La, Zr, Mg, and Pr.

6. The after treatment system of claim 4 , the composite of MgO and Al2O3 includes 15-25 wt % of MgO based on a total weight of the composite of MgO and Al2O3.

7. An after treatment system comprising:
an exhaust pipe through which an exhaust gas flows;
a three-way catalyst (TWC) mounted on the exhaust pipe and purifying HC, CO, and NOx contained in the exhaust gas;
an ammonia production catalyst (APC) mounted on the exhaust pipe at a downstream of the TWC, storing NOR at a lean air/fuel ratio, and generating H 2 , releasing the stored NOR, and generating NH 3 using the released NOR and the generated H 2 at a rich air/fuel ratio; and
a selective catalytic reduction (SCR) catalyst mounted on the exhaust pipe at a downstream of the APC, storing the NH 3 generated in the TWC and the APC, and reducing the NOR contained in the exhaust gas using the stored NH 3 , wherein the APC comprises Pt, Pd and CeO 2 , wherein a weight ratio of Pt to Pd is 3:1 to 7:1, and
wherein the NH 3 production in the APC is the greatest when the weight ratio of Pt to Pd is 4:1,
wherein weight ratio of the CeO 2 to a total weight of the APC is 10-25 wt %,
wherein a ratio of H 2 concentration increase to CeO 2 increase slows down if the CeO 2 exceeds 20 wt % based on the total weight of the APC, and
wherein the NH 3 production decreases due to increase of O 2 stored in the APC if the CeO 2 exceeds 30 wt % based on the total weight of the APC.

8. The after treatment system of claim 7 , wherein the APC comprises 0.4-0.9 wt % of Pt, 0.057-0.3 wt % of Pd, 0.03-0.1 wt % of Rh, 5.0-15.0 wt % of Ba, 10-25 wt % of CeO2, 48.7-79.513 wt % of a composite of MgO and Al2O3, and 0-10 wt % of an additive based on a total weight of the APC.

9. The after treatment system of claim 8 , wherein the additive comprises at least one of La, Zr, Mg, and Pr.

10. The after treatment system of claim 8 , the composite of MgO and Al2O3 includes 15-25 wt % of MgO based on a total weight of the composite of MgO and Al2O3.

11. The after treatment system of claim 7 , further comprising a CO cleanup catalyst (CUC) mounted on the exhaust pipe at a downstream of the SCR catalyst and purifying CO contained in the exhaust gas.

12. The after treatment system of claim 11 , further comprising a particulate filter disposed between the TWC and the APC or between the APC and the SCR catalyst,
wherein the particulate filter traps particulate matter in the exhaust gas.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Joo Nahm Roh
• Kim Chang Hwan
• Jung Changho

Classifications

• F01N2430/06

  by varying fuel-air ratio, e.g. by enriching fuel-air mixture · CPC title

• F01N3/2066

  Selective catalytic reduction [SCR] · CPC title

• F01N3/101

  Three-way catalysts · CPC title

• F01N3/021

  by means of filters · CPC title

• B01J2523/828

  Platinum · CPC title