Controlled pore size distribution porous ceramic honeycomb filter, honeycomb green body, batch mixture and manufacturing method therefor

• US 20070119135A1
• Filed: 11/30/2006
• Published: 05/31/2007
• Est. Priority Date: 11/30/2005
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Xie, Yuming, Wang, Jianguo, Miao, Weiguo, Shustack, Paul, Skolny, Jennifer
• Granted Patent: US 7,744,670 B2
• Time in Patent Office: Days
• US Class Current: 55/523
• CPC Class Codes: B01D 2239/10 Filtering material manufacturing
• CPC Class Codes: B01D 39/2068 Other inorganic materials, e.g. ceramics
• CPC Class Codes: C04B 2111/00129 Extrudable mixtures
• CPC Class Codes: C04B 2111/00793 as filters or diaphragms
• CPC Class Codes: C04B 2111/0081 as catalysts or catalyst carriers
• CPC Class Codes: C04B 2111/2084 Thermal shock resistance
• CPC Class Codes: C04B 2111/343 Crack resistant materials
• CPC Class Codes: C04B 35/195 Alkaline earth aluminosilicates, e.g. cordierite or anorthite
• CPC Class Codes: C04B 35/478 based on aluminium titanates
• CPC Class Codes: C04B 38/0006 Honeycomb structures from one or more corrugated sheets by winding or stacking C04B38/0083
• CPC Class Codes: C04B 38/0012 characterised by the material used for sealing or plugging (some of) the channels of the honeycombs
• CPC Class Codes: C04B 38/0054 the pores being microsized or nanosized
• CPC Class Codes: C04B 38/0074 expressed as porosity percentage
• CPC Class Codes: C04B 38/0645 Burnable, meltable, sublimable materials

Abstract

A porous ceramic honeycomb filter manufactured from an oxide-based ceramic material having a pore size distribution with d₁≧7.0 microns. Preferably, the oxide-based material is cordierite or aluminum titanate. Alternatively, the filter contains a cordierite-containing ceramic body with a narrow pore size distribution with d_b≦1.00, wherein d_b=(d₉₀−d₁₀)/d₅₀. Also disclosed is a batch mixture, method and honeycomb green body made from mixture of inorganic source materials selected from the group of magnesia sources, alumina sources, and silica sources, and a pore former having a narrow particle size distribution with d_ps≦0.90, wherein d_ps={(dp₉₀−dp₁₀)/dp₅₀}. The pore former is preferably selected from a group consisting of canna starch, sago palm starch, green mung bean starch, and single-mode potato starch.

Claims

1. A porous ceramic honeycomb filter, comprising:

an oxide-based ceramic material having many pores with a pore size distribution including d₁≧

7.0 microns, wherein d₁ is a pore diameter wherein 1.0% of a total pore volume of the pore size distribution has a smaller diameter.

2. The porous ceramic honeycomb filter of claim 1 oxide-based ceramic material is selected from a group consisting of cordierite and aluminum titanate.

3. The porous ceramic honeycomb filter of claim 2 wherein the filter comprises a diesel particulate filter.

4. The porous ceramic honeycomb filter of claim 2 wherein d₁≧

8.0 microns.

5. The porous ceramic honeycomb filter of claim 2 wherein d₁≧

9.0 microns.

6. The porous ceramic honeycomb filter of claim 1 further comprising:

d₁₀≧

10 μ

m,

d₅₀ of between 15 and 30 μ

m, and

d₉₀≦

45 μ

m

wherein d₁₀ is a pore size wherein 10% of the pore volume has a smaller pore diameter, d₅₀ is a median pore size wherein 50% of the pore volume has a smaller pore diameter, and d₉₀ is a pore size wherein 90% of the pore volume has a smaller pore diameter.

7. The porous ceramic honeycomb filter of claim 1 wherein the material comprises cordierite and d_f≦

0.38, wherein

d_f=(d₅₀−

d₁₀)/d₅₀

d₁₀ is a pore size where 10% of the pore volume has a smaller pore diameter, and

d₅₀ is a median pore size where 50% of the pore volume has a smaller pore diameter.

8. The porous ceramic honeycomb filter of claim 7 further comprising d_f≦

0.35.

9. The porous ceramic honeycomb filter of claim 7 further comprising d_f≦

0.30.

10. The porous ceramic honeycomb filter of claim 7 further comprising d_f≦

0.28.

11. The porous ceramic honeycomb filter of claim 7 further comprising d_f≦

0.25.

12. The porous ceramic honeycomb filter of claim 1 wherein the material comprises cordierite and d_b≦

1.00, wherein d_b=(d₉₀−

d₁₀)/d₅₀

and wherein d₁₀ is a pore size wherein 10% of the pore volume has a smaller pore diameter, d₅₀ is a median pore size wherein 50% of the pore volume has a smaller pore diameter, and d₉₀ is a pore size wherein 90% of the pore volume has a smaller pore diameter.

13. The porous ceramic honeycomb filter of claim 12 further comprising d_b≦

0.90.

14. The porous ceramic honeycomb filter of claim 12 further comprising d_b≦

0.85.

15. The porous ceramic honeycomb filter of claim 12 further comprising d_b≦

0.75.

16. The porous ceramic honeycomb filter of claim 1 comprising a total porosity (P) wherein P≧

40%.

17. The porous ceramic honeycomb filter of claim 16 comprising P≦

65%.

18. The porous ceramic honeycomb filter of claim 16 comprising P≦

55%.

19. The porous ceramic honeycomb filter of claim 1, comprising:

a porosity attributable to pores having a pore size less than 10 μ

m is less than 6%, and the porosity being attributable to pores having a pore size larger than 50 μ

m is less than 8%.

20. The porous ceramic honeycomb filter of claim 1 further comprising a plurality of parallel cell channels separated by porous walls wherein at least some of the parallel cell channels include end plugs.

21. The porous ceramic honeycomb filter of claim 1 further comprising a coefficient of thermal expansion (22-800°

C.) of less than or equal to 5.0×

10−

7/°

C.

22. The porous ceramic honeycomb filter of claim 1 further comprising a median pore diameter, d₅₀, of between 13 and 33 μ

m wherein d₅₀ is a median pore diameter where 50% of a pore volume of the distribution has a smaller pore diameter.

23. The porous ceramic honeycomb filter of claim 1, further comprising:

d₁≧

8.0 μ

m, and

porosity (P) wherein P<

55%.

24. The porous ceramic honeycomb filter of claim 1 wherein the pores are formed, at least in part, by burning out a pore former, wherein said pore former is a single-mode starch.

25. The porous ceramic honeycomb filter of claim 24 wherein the pore former is selected from a group consisting of canna starch, sago palm starch, green mung bean starch, and a single-mode potato starch.

26. The porous ceramic honeycomb filter of claim 1 wherein the oxide-based ceramic material comprises aluminum titanate.

27. The porous ceramic honeycomb filter of claim 26 further comprising d_f≦

0.25 wherein

d_f=(d₅₀−

d₁₀)/d₅₀

and wherein d₁₀ is a pore size where 10% of the pore volume has a smaller pore diameter, and

d₅₀ is a median pore size where 50% of the pore volume has a smaller pore diameter.

28. The porous ceramic honeycomb filter of claim 26 further comprising d_b≦

0.9, wherein d_b=(d₉₀−

d₁₀)/d₅₀

and wherein d₁₀ is a pore size wherein 10% of the pore volume has a smaller pore diameter, d₅₀ is a median pore size wherein 50% of the pore volume has a smaller pore diameter, and d₉₀ is a pore size wherein 90% of the pore volume has a smaller pore diameter.

29. A honeycomb green body, comprising:

a mixture of inorganic source materials selected from the group of magnesia sources, alumina sources, and silica sources, and a pore former having a particle size distribution with d_ps≦

0.90,

wherein d_ps={(dp₉₀−

dp₁₀)/dp₅₀} and the green body includes a honeycomb structure with a plurality of parallel channels

and wherein dp₁₀ is a particle size wherein 10% of the particle volume has a smaller particle diameter, dp₅₀ is a median particle size wherein 50% of the particle volume has a smaller particle diameter, and dp₉₀ is a particle size wherein 90% of the particle volume has a smaller particle diameter.

30. A honeycomb green body of claim 29, further comprising d_ps≦

0.85.

31. A honeycomb green body of claim 29, further comprising d_ps≦

0.80.

32. A honeycomb green body of claim 29, wherein the median particle size, dp₅₀, of the pore former is between 20 μ

m and 50 μ

m.

33. The honeycomb green body of claim 29 wherein the pore former is a single-mode starch.

34. The honeycomb green body of claim 29 wherein the pore former is selected from a group of starches consisting of canna starch, sago palm starch, green mung bean starch, and single-mode potato starch.

35. The green body of claim 29 wherein the pore former is canna starch.

36. The green body of claim 29 wherein the pore former is sago palm starch.

37. The green body of claim 29 wherein the pore former is green mung bean starch.

38. The green body of claim 29 wherein the pore former is single-mode potato starch.

39. The green body of claim 29 wherein the pore former comprises between 5-30 wt. % of the inorganic materials.

40. The green body of claim 39 wherein the pore former comprises between 5-15 wt. % of the inorganic materials.

41. A batch mixture for a forming a porous ceramic honeycomb article, comprising:

a mixture of inorganic source materials and a pore former, wherein the pore former has a particle size distribution with d_ps≦

0.90,

wherein d_ps=(dp₉₀−

dp₁₀)/dp₅₀

and wherein dp₁₀ is a particle size wherein 10% of the particle volume has a smaller particle size, dp₅₀ is a median particle size wherein 50% of the particle volume has a smaller particle size, and dp₉₀ is a particle size wherein 90% of the particle volume has a smaller particle size.

42. The batch of claim 41 further comprising d_ps≦

0.85.

43. The batch of claim 41 further comprising d_ps≦

0.80.

44. The batch of claim 41 wherein the pore former is a single-moded.

45. The batch of claim 41 wherein the pore former is a starch.

46. The batch of claim 45 wherein the starch is selected from a group consisting of canna starch, sago palm starch, green mung bean starch, and single-mode potato starch.

47. The batch of claim 46 wherein the starch has a median particle size, dp₅₀, of the pore former is between 20 μ

m and 50 μ

m.

48. The batch of claim 41 wherein the pore former comprises between 5-30 wt. % of the inorganic source materials.

49. A batch mixture for forming a ceramic honeycomb article, comprising:

a mixture of inorganic material sources and a pore former selected from a group consisting of canna starch, sago palm starch, green mung bean starch, and single-mode potato starch

whereas a desired level of porosity may be achieved in the ceramic honeycomb article by using relatively less pore former than graphite.

50. The batch mixture of claim 49 wherein the inorganic material sources include at least two selected from a group consisting of a magnesia source, an alumina source, a silica source, and a titania source.

51. A method of manufacturing a honeycomb article, comprising the steps of:

mixing inorganic material sources and a pore former with forming aids to form a plasticized batch, wherein the pore former has a particle size distribution with d_ps≦

0.9, wherein d_ps=(dp₉₀−

dp₁₀)/dp₅₀ and dp₁₀ is a particle size wherein 10% of the particle volume has a smaller particle size, dp₅₀ is a median particle size wherein 50% of the particle volume has a smaller particle size, and dp₉₀ is a particle size wherein 90% of the particle volume has a smaller particle size, and

forming the plasticized batch into the honeycomb article.

52. The method of manufacturing of claim 51 wherein the pore former comprises a single-moded starch.

53. The method of manufacturing of claim 51 wherein the pore former is selected from a group consisting of sago palm starch, green mung bean starch, canna starch, and single-mode potato starch.

54. The method of manufacturing of claim 51 further comprising d_ps≦

0.85.

55. A porous ceramic honeycomb filter, comprising:

a cordierite-containing ceramic body, the body having an inlet end and an outlet end, and a multiplicity of cell channels at least partially defined by porous cell walls, said walls extending from the inlet end to the outlet end, wherein some of the cell channels are plugged, said porous cell walls including a material with many pores and having a pore size distribution with d_b≦

1.00, wherein d_b=(d₉₀−

d₁₀)/d₅₀

wherein

d₁₀ is a pore size wherein 10% of the pore volume has a smaller pore diameter,

d₅₀ is a median pore size wherein 50% of the pore volume has a smaller pore diameter, and

d₉₀ is a pore size wherein 90% of the pore volume has a smaller pore diameter.

56. The porous ceramic honeycomb filter claim 55 further comprising d_b≦

0.90.

57. The porous ceramic honeycomb filter of claim 55 further comprising d_b≦

0.85.

58. The porous ceramic honeycomb filter of claim 55 further comprising d_b≦

0.75.

59. The porous ceramic honeycomb filter of claim 57 comprising a total porosity (P) wherein P≧

40%.

60. The porous ceramic honeycomb filter of claim 59 further comprising:

porosity (P) wherein P≦

55%.

61. The porous ceramic honeycomb filter of claim 59 further comprising a coefficient of thermal expansion (22-800°

C.) of less than 10.0×

10<sup>−

7</sup>/°

C.

62. The porous ceramic honeycomb filter of claim 61 further comprising a coefficient of thermal expansion (22-800°

C.) of less than or equal to 5.0×

10<sup>−

7</sup>/°

C.

63. The porous ceramic honeycomb filter of claim 61 further comprising a coefficient of thermal expansion (22-800°

C.) of less than or equal to 4.0×

10<sup>−

7</sup>/°

C.

64. The porous ceramic honeycomb filter of claim 59 further comprising d₁≧

7.0 μ

m, wherein d₁ is a pore size wherein 1% of a total pore volume of the pore size distribution has a smaller pore diameter.

65. The porous ceramic honeycomb filter of claim 64 further comprising d₁≧

8.0 μ

m.

66. The porous ceramic honeycomb filter of claim 59 wherein the material comprises d_f≦

0.38, wherein d_f=(d₅₀−

d₁₀)/d₅₀

and wherein d₁₀ is a pore size wherein 10% of the pore volume has a smaller pore diameter, and d₅₀ is a median pore size wherein 50% of the pore volume has a smaller pore diameter.

67. The porous ceramic honeycomb filter of claim 66 further comprising d_f≦

0.35.

68. The porous ceramic honeycomb filter of claim 66 further comprising d_f≦

0.30.

69. The porous ceramic honeycomb filter of claim 66 further comprising d_f≦

0.28.

70. The porous ceramic honeycomb filter of claim 66 further comprising d_f≦

0.25.