Diesel oxidation catalyst

Patent metadata

Field	Value
Publication number	US-10328388-B2
Application number	US-201615748501-A
Country	US
Kind code	B2
Filing date	Jul 29, 2016
Priority date	Jul 30, 2015
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

An oxidation catalyst composite, methods, and systems for the treatment of exhaust gas emis-sions from a diesel engine are described. More particularly, described is an oxidation catalyst composite including a first oxidation material comprising a first refractory metal oxide support, a rare earth oxide, and palladium (Pd); a second oxidation material comprising a second refractory metal oxide, and platinum (Pt) and palladium (Pd); and a protective overlayer comprising a third refractory metal oxide, platinum (Pt) and, optionally, palladium (Pd), and a molecular sieve promoted with a metal selected from one or more of Cu, Fe, Co, Ni, Mn, V, and, Ag. The oxid-ation catalyst composite is sulfur tolerant.

First claim

The invention claimed is:

1. An oxidation catalyst composite for abatement of exhaust gas emissions from a lean burn engine, the catalyst composite comprising:
a carrier substrate having a length, an inlet end and an outlet end, an oxidation catalyst material on the carrier, the oxidation catalyst material comprising:
a first oxidation material including a first refractory metal oxide support, a rare earth oxide component, and palladium (Pd), the first oxidation material being substantially free of platinum;
a second oxidation material including a second refractory metal oxide support, and platinum (Pt) and palladium (Pd) in a platinum to palladium ratio of 10:1 to 1:10, the second oxidation material being substantially free of rare earth oxide; and
a protective overlayer including a third refractory metal oxide, platinum (Pt) and, optionally, palladium (Pd), and a molecular sieve promoted with a metal selected from one or more of Cu, Fe, Co, Ni, Mn, V, and Ag, the protective overlayer being substantially free of a rare earth oxide.

2. The oxidation catalyst composite of claim 1 , wherein the first oxidation material is in an underlayer on the carrier substrate, the second oxidation material is in a middle layer on the under layer, and the protective overlayer is in an upper layer on the middle layer.

3. The oxidation catalyst composite of claim 1 , wherein the first oxidation material and second oxidation material are mixed in a blended underlayer on the carrier substrate, and the protective overlayer is an upper layer on the blended underlayer.

4. The oxidation catalyst composite of claim 1 , wherein the first oxidation material and the second oxidation material are in a zoned underlayer on the carrier substrate, and the protective overlayer is an upper layer on the zoned underlayer.

5. The oxidation catalyst composite of claim 4 , wherein the first oxidation material is on the inlet end and the second oxidation material is on the outlet end.

6. The oxidation catalyst composite of claim 4 , wherein the second oxidation material is on the inlet end and the first oxidation material is on the outlet end.

7. The oxidation catalyst composite of claim 1 , wherein the first, second, and third refractory metal oxide supports independently comprise an oxide of one or more of alumina, zirconia, alumina-zirconia, lanthana-alumina, lanthana-zirconia-alumina, baria-alumina, baria-lanthana-alumina, baria-lanthana-neodymia-alumina, alumina-chromia.

8. The oxidation catalyst composite of claim 1 , wherein the first oxidation material comprises palladium in an amount in the range of about 1 g/ft 3 to 70 g/ft 3 , and wherein the second oxidation material comprises palladium and platinum in an amount in the range of about 5 g/ft 3 to about 150 g/ft 3 .

9. The oxidation catalyst composite of claim 1 , wherein the rare earth oxide is selected from ceria (Ce), lanthana (La), praseodymia (Pr), neodynmia (Nd), europia (Eu), samaria (Sm), ytterbia (Yb), and combinations thereof, and a stabilizer optionally mixed therein, the stabilizer selected from zirconia (Zr), niobia (Nb), yttria (Y), alumina (Al), and combinations thereof.

10. The oxidation catalyst composite of claim 1 , wherein the ratio of Pd to the rare earth oxide is in the range of 1 to 5 by weight, based on the weight of the first oxidation material.

11. The oxidation catalyst composite of claim 1 , wherein the rare earth oxide component in the first oxidation material is present in an amount in the range 0.1 g/in 3 to 5 g/in 3 .

12. The oxidation catalyst composite of claim 1 , wherein the rare earth oxide component in the first oxidation material comprises ceria (Ce).

13. The oxidation catalyst composite of claim 12 , wherein the Ce is doped with an element selected from Si, Mn, Fe, Co, Ni, Cu, In, Sn, Ir, Pr, and combinations thereof.

14. The oxidation catalyst composite of claim 1 , wherein the protective overlayer comprises a molecular sieve having a six, eight, ten, or twelve ring structure.

15. The oxidation catalyst composite of claim 1 , wherein the molecular sieve is selected from the group consisting of Type A, chabazite, erionite, ZSM-5, ZSM-11, ZSM-23, ZSM-48, ferrierite, stilbite, faujasite, mordenite, Type L, Omega, Beta, AlPO 4 , borosilicates, MeAPO, MeAPSO, and SAPO.

16. The oxidation catalyst composite of claim 1 , wherein the ratio of platinum to palladium in the second oxidation material is in the range of 5:1 to 1:5.

17. The oxidation catalyst composite of claim 1 , wherein the ratio of platinum to palladium in the second oxidation material is in the range of 2:1 to 1:1.

18. The oxidation catalyst composite of claim 1 , wherein the carrier substrate is selected from a flow-through monolith, a wall-flow filter, a foam, or a mesh.

19. A method for treating a diesel engine exhaust gas stream, the method comprising contacting an exhaust gas stream with the oxidation catalyst composite of of claim 1 , and passing the exhaust gas stream through a downstream SCR catalyst.

20. The method of claim 19 , wherein the downstream SCR catalyst is disposed on a wall flow filter.

21. A system for treatment of a lean burn engine exhaust gas stream comprising hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter, and other exhaust components, the system comprising:
an exhaust conduit in fluid communication with a lean burn engine via an exhaust manifold;
the oxidation catalyst composite of claim 1 ; and
a catalyzed soot filter and an SCR catalyst located downstream from the oxidation catalyst composite.

22. The system of claim 21 , wherein the SCR catalyst is present as a washcoat on the catalyzed soot filter.

23. The system of claim 22 , further comprising a second SCR catalyst on a flow through monolith downstream of the SCR catalyst.

24. The system of claim 21 , wherein the SCR catalyst is on a flow through monolith downstream from the oxidation catalyst composite, and the catalyzed soot filter is downstream from the SCR catalyst.

25. The system of claim 21 , wherein the catalyzed soot filter is downstream of the oxidation catalyst composite and the SCR catalyst is on a flow through monolith downstream from the catalyzed soot filter.

26. The system of claim 24 , wherein the catalyzed soot filter comprises a second SCR catalyst.

27. The system of claim 21 , wherein the SCR catalyst comprises a molecular sieve having a double six ring (d6r) unit.

28. The system of claim 21 , wherein the SCR catalyst is selected from CHA, AEI, or AFX framework type zeolite.

Assignees

• Basf Corp

Inventors

• Dumbuya Karifala
• Zabel Claudia
• Stiebels Susanne
• Sung Shiang

Classifications

• B01D2255/2065

  Cerium · CPC title

• B01D2255/502

  Beta zeolites · CPC title

• B01D2255/2063

  Lanthanum · CPC title

• B01D2255/9025

  Three layers · CPC title

• B01D2255/9022

  Two layers · CPC title