Passive NOx adsorber

Patent metadata

Field	Value
Publication number	US-10005075-B2
Application number	US-201414563340-A
Country	US
Kind code	B2
Filing date	Dec 8, 2014
Priority date	Dec 6, 2013
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

A passive NO x adsorber is disclosed. The passive NO x adsorber is effective to adsorb NO x at or below a low temperature and release the adsorbed NO x at temperatures above the low temperature. The passive NO x adsorber comprises a noble metal and a small pore molecular sieve. The small pore molecular sieve has a maximum ring size of eight tetrahedral atoms. The invention also includes an exhaust system comprising the passive NO x adsorber, and a method for treating exhaust gas from an internal combustion engine utilizing the passive NO x adsorber.

First claim

We claim:

1. A passive NO x adsorber effective to adsorb NO x at or below a low temperature and release the adsorbed NO x at temperatures above the low temperature, said passive NO x adsorber comprising a noble metal and a small pore molecular sieve having a maximum ring size of eight tetrahedral atoms:
wherein greater than 5 percent of the total amount of noble metal is located inside pores of the small pore molecular sieve.

2. The passive NO x adsorber of claim 1 wherein the noble metal is selected from the group consisting of platinum, palladium, rhodium, gold, silver, iridium, ruthenium, osmium, and mixtures thereof.

3. The passive NO x adsorber of claim 1 wherein the noble metal is palladium.

4. The passive NO x adsorber of claim 1 wherein the small pore molecular sieve is selected from the group consisting of aluminosilicate molecular sieves, metal-substituted aluminosilicate molecular sieves, aluminophosphate molecular sieves and metal-substituted aluminophosphate molecular sieves.

5. The passive NO x adsorber of claim 1 wherein the small pore molecular sieve is selected from the group of Framework Type consisting of: ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON, and mixtures or intergrowths thereof.

6. The passive NO x adsorber of claim 1 wherein the small pore molecular sieve is selected from the group Framework Type consisting of AEI and CHA.

7. The passive NO x adsorber of claim 5 wherein the intergrowths of the small pore molecular sieves include KFI-SIV, ITE-RTH, AEW-UEI, AEI-CHA, and AEI-SAV.

8. The passive NO x adsorber of claim 1 wherein the passive NO x adsorber is coated onto a flow-through or filter substrate.

9. The passive NO x adsorber of claim 8 wherein the flow-through substrate is a honeycomb monolith.

10. The passive NO x adsorber of claim 1 wherein the passive NO x adsorber is extruded to form a flow-through or filter substrate.

11. The passive NO x adsorber of claim 1 wherein the low temperature is 200° C.

12. An exhaust system for internal combustion engines comprising the passive NO x adsorber of claim 1 and a catalyst component selected from the group consisting a selective catalytic reduction (SCR) catalyst, a particulate filter, a SCR filter, a NO x adsorber catalyst, a three-way catalyst, an oxidation catalyst, and combinations thereof.

13. A method for reducing NO x in an exhaust gas, said method comprising adsorbing NO x onto the passive NO x adsorber of claim 1 at or below a low temperature, thermally desorbing NO x from the passive NO x adsorber at a temperature above the low temperature, and catalytically removing the desorbed NO x on a catalyst component downstream of the passive NO x adsorber.

14. The method of claim 13 wherein the catalyst component is selected from the group consisting a selective catalytic reduction (SCR) catalyst, a particulate filter, a SCR filter, a NO x adsorber catalyst, a three-way catalyst, an oxidation catalyst, and combinations thereof.

15. The method of claim 14 wherein the low temperature is 200° C.

Assignees

• Johnson Matthey Plc

Inventors

• Rajaram Raj Rao
• Chen Hai-Ying
• Liu Dongxia

Classifications

• B01J20/3238

  containing any type of zeolite · CPC title

• B01J29/44

  Noble metals · CPC title

• B01J29/74

  Noble metals · CPC title

• B01D2255/50

  Zeolites · CPC title

• B01J20/3204

  Inorganic carriers, supports or substrates · CPC title