Catalyst with Lanthanide-Doped Zirconia and Methods of Making

• US 20130115144A1
• Filed: 08/08/2012
• Published: 05/09/2013
• Est. Priority Date: 08/10/2011
• Status: Active Grant

• Current Assignee: Clean Diesel Technologies, Inc.
• Original Assignee: Clean Diesel Technologies, Inc.
• Inventors: Golden, Stephen J., Hatfield, Randal, Pless, Jason D.
• Granted Patent: US 9,011,784 B2
• Time in Patent Office: Days
• US Class Current: 422/170
• CPC Class Codes: B01J 23/002 Mixed oxides other than spinels, e.g. perovskite
• CPC Class Codes: B01J 23/10 of rare earths
• CPC Class Codes: B01J 23/464 Rhodium
• CPC Class Codes: B01J 23/63 with rare earths or actinides
• CPC Class Codes: B01J 2523/00 Constitutive chemical elements of heterogeneous catalysts
• CPC Class Codes: B01J 2523/36 Yttrium
• CPC Class Codes: B01J 2523/3712 Cerium
• CPC Class Codes: B01J 2523/3718 Praseodymium
• CPC Class Codes: B01J 2523/3725 Neodymium
• CPC Class Codes: B01J 2523/48 Zirconium
• CPC Class Codes: B01J 35/00 Catalysts, in general, characterised by their form or physical properties
• CPC Class Codes: B01J 35/19 Catalysts containing parts with different compositions
• CPC Class Codes: B01J 35/30 characterised by their physical properties
• CPC Class Codes: B01J 35/40 characterised by dimensions, e.g. grain size in a colloidal state B01J35/23; crystallite size B01J35/77
• CPC Class Codes: B01J 37/0036 Grinding
• CPC Class Codes: B01J 37/0201 Impregnation
• CPC Class Codes: B01J 37/0236 Drying, e.g. preparing a suspension, adding a soluble salt and drying
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: B01J 37/038 to form slurries or suspensions, e.g. a washcoat
• CPC Class Codes: C01F 17/32 oxide or hydroxide being the only anion, e.g. NaCeO2 or MgxCayEuO
• CPC Class Codes: C01G 25/00 : Compounds of zirconium
• CPC Class Codes: C01G 25/02 : Oxides
• CPC Class Codes: C01P 2002/52 : containing elements as dopants
• CPC Class Codes: C01P 2002/54 : one element only
• CPC Class Codes: C01P 2002/72 : by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C04B 2235/3205 : Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
• CPC Class Codes: C04B 2235/3224 : Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3227 : Lanthanum oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 : Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 35/486 : Fine ceramics
• CPC Class Codes: C04B 35/488 : Composites
• CPC Class Codes: C04B 35/50 : based on rare-earth compounds non-oxide rare earth compounds C04B35/5156

Abstract

The invention generally relates to three-way catalysts and catalyst formulations capable of simultaneously converting nitrogen oxides, carbon monoxide, and hydrocarbons into less toxic compounds. Such three-way catalyst formulations contain ZrO₂-based mixed-metal oxide support oxides doped with an amount of lanthanide. Three-way catalyst formulations with the support oxides of the present invention demonstrate higher catalytic activity, efficiency and longevity than comparable catalysts formulated with traditional support oxides.

Claims

1. A support oxide comprising ZrO₂ doped with an amount of lanthanide.

2. The support oxide of claim 1, wherein said support oxide further comprises Al₂O₃ or La—

Al₂O₃.

3. The support oxide of claim 1, wherein said lanthanide is La or Pr.

4. The support oxide of claim 1, wherein the ZrO₂ is doped with between about 1-30% of said lanthanide.

5. The support oxide of claim 4, wherein the ZrO₂ is doped with between about 5-15% of said lanthanide.

6. The support oxide of claim 1, wherein said support oxide comprises La_{X %}Zr_{(1-X) %}O₂ and/or Pr_{X %}Zr_{(1-X) %}O₂.

7. The support oxide of claim 6, wherein said support oxide comprises La_5%Zr_95%O₂, Pr_5%Zr_95%O₂, La_10%Zr_90%O₂, Pr_10%Zr_90%O₂, La_15%Zr_85%O₂, Pr_15%Zr_85%O₂, or mixtures thereof.

8. The support oxide of claim 1, wherein said support oxide is in the tetragonal phase.

9. The support oxide of claim 1, wherein said support oxide further comprises an oxygen storage material (OSM).

10. A washcoat or overcoat comprising a support oxide, an oxygen storage material (OSM) and a catalyst, wherein said support oxide is according to claim 1.

11. The washcoat or overcoat of claim 10, wherein said catalyst is a platinum group metal (PGM) catalyst.

12. The washcoat or overcoat of claim 11, wherein said PGM is Rh, Pt, Pd, or a mixture thereof.

13. The washcoat or overcoat of claim 12, wherein said PGM is Rh.

14. The washcoat or overcoat of claim 13, wherein said Rh is present at 0.25% (by weight) of said washcoat.

15. The washcoat or overcoat of claim 10, wherein said support oxide constitutes 1-100% (by weight) of said washcoat or overcoat.

17. A washcoat or overcoat according to claim 15, wherein said OSM is:

Ce_1-a-b-c-dD_aE_bF_cZr_dO₂, wherein;

a, b and c are, independently, 0-0.7;

d is 0-0.9; and

D, E and F are, independently, selected from the group consisting of lanthanides, alkaline earth metals and transition metals.

18. A washcoat or overcoat according to claim 17, wherein said OSM is Ce_0.3Nd_0.05Pr_0.05Zr_0.6O₂.

19. A catalyst system comprising:

a substrate and a washcoat,

wherein said washcoat is according to claim 10.

20. A catalyst system comprising:

a substrate, a washcoat, and an overcoat,

wherein said washcoat is according to claim 10; and

said overcoat comprises a support oxide, an oxygen storage material (OSM), and a catalyst.

21. A catalyst system comprising:

a substrate, a washcoat, and an overcoat,

wherein said washcoat comprises a support oxide, an oxygen storage material (OSM) and a catalyst; and

wherein said overcoat is according to claim 10.

22. The catalyst system of claim 21, wherein said catalyst in said overcoat is a platinum group metal (PGM) catalyst.

23. The catalyst system of claim 22, wherein said catalyst in said overcoat is Rh, Pt, Pd, or a mixture thereof.

24. The catalyst system of claim 23, wherein said catalyst in said overcoat is Pd.

25. The catalyst system of claim 24, wherein said Pd is present at 100 g/ft³.

26. The catalyst system of claim 21, wherein said catalyst in said washcoat is a platinum group metal (PGM) catalyst.

27. The catalyst system of claim 26, wherein said catalyst in said washcoat is Rh, Pt, Pd, or a mixture thereof.

28. The catalyst system of claim 27, wherein said catalyst in said washcoat is Pd.

29. The catalyst of claim 28, wherein said Pd is present at 100 g/ft³.

30. The catalyst system of claim 19, wherein said catalyst system is a three way conversion catalyst system.

31. The catalyst system of claim 19, wherein said catalyst system exhibits improved gas flow when compared to catalyst systems comprising only traditional support oxides.

32. The catalyst system of claim 19, wherein said catalyst system exhibits improved light-off performance when compared to catalyst systems comprising only traditional support oxides.

33. A method of making a catalyst system comprising:

a) depositing a washcoat according to claim 10 on a substrate;

b) treating said washcoat and substrate by calcination; and

c) optionally impregnating a platinum group metal (PGM) catalyst into said washcoat, followed by drying and calcination.

34. A method of making a catalyst system comprising:

a) depositing a washcoat according to claim 10 on a substrate;

b) treating said washcoat and substrate by calcination;

c) optionally impregnating a platinum group metal (PGM) catalyst into said washcoat, followed by drying and calcination;

d) depositing an overcoat onto the washcoat;

wherein said overcoat comprises a support oxide, an oxygen storage material and a catalyst;

e) optionally impregnating a PGM catalyst into said overcoat, followed by drying and calcination.

35. A method of making a catalyst system comprising:

a) depositing a washcoat on a substrate,

wherein said washcoat comprises a support oxide, an oxygen storage material and a catalyst;

b) treating said washcoat and substrate by calcination;

c) optionally impregnating a platinum group metal (PGM) catalyst into said washcoat, followed by drying and calcination;

d) depositing an overcoat according to claim 10 onto the washcoat;

e) optionally impregnating a PGM catalyst into said overcoat, followed by drying and calcination.

16. A washcoat or overcoat comprising:

a) (i) 40% oxygen storage material (OSM);

(ii) 30% Al₂O₃ or La-Al₂O₃; and

(iii) 30% Pr_0.05Zr_0.95O₂;

b) (i) 40% OSM;

(ii) 30% Al₂O₃ or La—

Al₂O₃; and

(iii) 30% La_0.05Zr_0.95O₂;

c) (i) 40% OSM;

30% Al₂O₃ or La—

Al₂O₃; and

(iii) 30% Pr_0.10Zr_0.90O₂;

d) (i) 40% OSM;

30% Al₂O₃ or La—

Al₂O₃; and

(iii) 30% La_0.10Zr_0.90O₂;

e) (i) 40% OSM;

30% Al₂O₃ or La—

Al₂O₃; and

(iii) 30% Pr_0.15Zr_0.85O₂;

(i) 40% OSM;

30% Al₂O₃ or La—

Al₂O₃; and

(iii) 30% La_0.15Zr_0.85O₂;

g) (i) 40% OSM; and

(ii) 60% Pr_0.05Zr_0.95O₂;

h) (i) 40% OSM; and

(ii) 60% La_0.05Zr_0.95O₂;

i) (i) 40% OSM; and

(ii) 60% Pr_0.10Zr_0.90O₂;

j) (i) 40% OSM; and

(ii) 60% La_0.10Zr_0.90O₂;

k) (i) 40% OSM; and

(ii) 60% Pr_0.15Zr_0.85O₂;

or

l) (i) 40% OSM; and

(ii) 60% La_0.15Zr_0.85O₂.

36. A catalyst system comprising an overcoat, wherein said overcoat comprises an oxygen storage material (OSM) and a support oxide in a 1.5:

1 ratio (by weight), wherein;

said OSM is 30% CeO₂, 60% ZrO₂, 5% Nd₂O₃, and 5% Pr₆O₁₁ (by weight); and

said support oxide is Pr_0.10Zr_0.90O₂.

37. The catalyst system of claim 36, wherein said catalyst system further comprises a washcoat, wherein said washcoat comprises an OSM and a support oxide in a 1.5:

1 ratio (by weight), wherein;

said OSM is 30% CeO₂, 60% ZrO₂, 5% Nd₂O₃ and 5% Pr₆O₁₁ (by weight); and

said support oxide is La—

Al₂O₃.

38. A catalytic convertor system comprising the catalyst system of claim 36.

39. The catalytic convertor system of claim 38, wherein said catalytic convertor comprises two or more catalytic converters.

40. The catalytic convertor system of claim 39, wherein said catalytic convertor system comprises a close coupled catalytic converter.