Catalyst design for heavy-duty diesel combustion engines

1. A coated substrate comprising:

a substrate;

a first washcoat layer comprising:

boehmite particles; and

a first catalytically active material comprising platinum and palladium in a weight ratio of 10:1 platinum:palladium to 100:1 platinum:palladium, or comprising platinum and no palladium; and

a second washcoat layer comprising:

boehmite particles; and

a second catalytically active material comprising:

i. platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium;

ii. two or more catalytically active materials which together comprise platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium; or

iii. palladium and no platinum.

2. The coated substrate of claim 1 , wherein the catalytic washcoat layers are substantially free of zeolites.

3. The coated substrate of claim 1 , wherein the first catalytically active material or the second catalytically active material comprises

plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle.

4. The coated substrate of claim 1 , wherein the first catalytically active material or the second catalytically active material comprises micron-sized particles comprising plasma-created composite nanoparticles embedded within the micron-sized particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle.

5. The coated substrate of claim 1 , wherein the first catalytically active material comprises hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with platinum or platinum:palladium alloy.

6. The coated substrate of claim 1 , wherein the first catalytically active material comprises catalytic particles produced by only wet-chemistry methods, comprising a micron-sized particle impregnated by only wet-chemistry methods with platinum or platinum:palladium alloy.

7. The coated substrate of claim 1 , wherein the second catalytically active material comprises hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with palladium or platinum:palladium alloy.

8. The coated substrate of claim 1 , wherein the second catalytically active material comprises catalytic particles produced by only wet-chemistry methods, comprising a micron-sized particle impregnated by only wet-chemistry methods with palladium or platinum:palladium alloy.

9. The coated substrate of claim 1 , wherein:

the second washcoat layer comprises two or more catalytically active materials which together comprise platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium; and

the two or more catalytically active materials together comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium comprise:

i) a catalyst comprising platinum:palladium alloy in a ratio of about 15:1 Pt:Pd to about 25:1 Pt:Pd; and

ii) a catalyst comprising palladium.

10. The coated substrate of claim 1 , wherein:

the second washcoat layer comprises two or more catalytically active materials which together comprise platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium; and

the two or more catalytically active materials together comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium comprise

a) plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, wherein the catalytic nanoparticle comprises a platinum:palladium alloy in a ratio of about 15:1 Pt:Pd to about 25:1 Pt:Pd; and

b) a catalyst comprising palladium.

11. The coated substrate of claim 1 , wherein the two or more catalytically active materials together comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium comprise:

a) micron-sized particles comprising plasma-created composite nanoparticles embedded within the micron-sized particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, wherein the catalytic nanoparticle comprises a platinum:palladium alloy in a ratio of about 15:1 Pt:Pd to about 25:1 Pt:Pd; and

b) micron-sized carrier particles impregnated with palladium by wet-chemistry methods.

12. The coated substrate of claim 1 , wherein the two or more catalytically active materials together comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium comprise:

a) hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with palladium or platinum:palladium alloy, wherein the hybrid particles comprise a total content of platinum:palladium in a ratio of about 15:1 Pt:Pd to about 25:1 Pt:Pd; and

b) micron-sized carrier particles impregnated with palladium by wet-chemistry methods.

13. The coated substrate according to claim 1 , wherein the washcoat layer or washcoat layers further comprises filler particles.

14. The coated substrate of claim 13 , wherein the filler particles comprise alumina.

15. The coated substrate of claim 1 , wherein the washcoat layer comprising the second catalytically active material further comprises a third catalytically active material selected from the group consisting of:

plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle;

micron-size particles comprising plasma-created composite nanoparticles embedded within the micron-sized particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle;

hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with platinum, palladium, or platinum:palladium alloy; and

catalytic particles produced by only wet-chemistry methods, comprising a micron-sized particle impregnated by only wet-chemistry methods with platinum, palladium, or platinum:palladium alloy;

wherein said third catalytically active material is different from the second catalytically active material.

16. A coated substrate comprising:

a substrate; and

a washcoat layer comprising:

boehmite particles;

a first catalytically active material comprising platinum and palladium in a weight ratio of 10:1 platinum:palladium to 100:1 platinum:palladium, or comprising platinum and no palladium; and

a second catalytically active material comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium, or comprising palladium and no platinum.

17. The coated substrate of claim 16 , wherein the washcoat layer containing the first catalytically active material and the second catalytically active material is substantially free of zeolites.

18. The coated substrate of claim 16 , wherein the first catalytically active material comprises

a) plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle; or

b) micron-sized particles comprising plasma-created composite nanoparticles embedded within the micron-sized particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle; or

c) hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with platinum or platinum:palladium alloy; or

d) catalytic particles produced by only wet-chemistry methods, comprising a micron-sized particle impregnated by only wet-chemistry methods with platinum or platinum:palladium alloy.

19. The coated substrate of claim 16 , wherein the second catalytically active material comprises:

a) plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle; or

b) micron-sized particles comprising plasma-created composite nanoparticles embedded within the micron-sized particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle; or

c) hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with palladium or platinum:palladium alloy; or

d) catalytic particles produced by only wet-chemistry methods, comprising a micron-sized particle impregnated by only wet-chemistry methods with palladium or platinum:palladium alloy.

20. The coated substrate of claim 16 , wherein the second catalytically active material comprises two or more catalytically active materials which together comprise platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium.

21. The coated substrate of claim 16 , wherein the washcoat layer or washcoat layers further comprises filler particles.

22. The coated substrate of claim 16 , wherein the washcoat layer comprising the second catalytically active material further comprises a third catalytically active material selected from the group consisting of:

plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle;

micron-size particles comprising plasma-created composite nanoparticles embedded within the micron-sized particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle;

hybrid particles comprising plasma-created composite nanoparticles bonded to pre-formed micron-sized carrier particles, wherein the composite nanoparticles comprise a support nanoparticle and a catalytic nanoparticle, and wherein the micron-sized pre-formed carrier particles are impregnated by wet-chemistry methods with platinum, palladium, or platinum:palladium alloy; and

catalytic particles produced by only wet-chemistry methods, comprising a micron-sized particle impregnated by only wet-chemistry methods with platinum, palladium, or platinum:palladium alloy;

wherein said third catalytically active material is different from the second catalytically active material.

23. A method of forming a coated substrate comprising coating a substrate with a washcoat layer comprising:

boehmite particles;

a first catalytically active material comprising platinum and palladium in a weight ratio of 10:1 platinum:palladium to 100:1 platinum:palladium, or comprising platinum and no palladium; and

a second catalytically active material comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium, or comprising palladium and no platinum.

24. A method of forming a coated substrate comprising, in either order:

coating a substrate with a first washcoat layer comprising:

boehmite particles; and

a first catalytically active material comprising platinum and palladium in a weight ratio of 10:1 platinum:palladium to 100:1 platinum:palladium, or comprising platinum and no palladium; and

coating the substrate with a second washcoat layer comprising:

boehmite particles; and

a second catalytically active material comprising platinum and palladium in a weight ratio of 1:2 platinum:palladium to 8:1 platinum:palladium, or comprising palladium and no platinum.