METHOD FOR PRODUCING POROUS BODIES WITH ENHANCED PROPERTIES

• US 20160354759A1
• Filed: 06/02/2016
• Published: 12/08/2016
• Est. Priority Date: 06/02/2015
• Status: Active Grant

• Current Assignee: Scientific Design Company, Inc. (Clariant AG)
• Original Assignee: Scientific Design Company, Inc. (Clariant AG)
• Inventors: Julian, Matthew, Suchanek, Wojciech L.
• Granted Patent: US 10,124,318 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B01J 19/0013 Controlling the temperature of the process
• CPC Class Codes: B01J 21/04 Alumina
• CPC Class Codes: B01J 2219/00051 Controlling the temperature
• CPC Class Codes: B01J 23/04 Alkali metals
• CPC Class Codes: B01J 23/36 Rhenium
• CPC Class Codes: B01J 23/50 Silver
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 35/612 less than 10 m2/g
• CPC Class Codes: B01J 35/633 less than 0.5 ml/g
• CPC Class Codes: B01J 35/635 0.5-1.0 ml/g
• CPC Class Codes: B01J 35/638 more than 1.0 ml/g
• CPC Class Codes: B01J 35/66 Pore distribution
• CPC Class Codes: B01J 37/0018 Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
• CPC Class Codes: B01J 37/086 Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
• CPC Class Codes: C04B 2111/0081 as catalysts or catalyst carriers
• CPC Class Codes: C04B 35/10 based on aluminium oxide
• CPC Class Codes: C04B 38/00 Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof treating slag with gases or gas generating material C04B5/06 ; expanded graphite C04B35/536
• CPC Class Codes: C04B 38/0096 Pores with coated inner walls
• CPC Class Codes: C04B 38/08 by adding porous substances
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4535 : applied as a solution, emulsion, dispersion or suspension
• CPC Class Codes: C04B 41/455 : the coating or impregnating process including a chemical conversion or reaction
• CPC Class Codes: C04B 41/5116 : Ag or Au
• CPC Class Codes: C04B 41/88 : Metals
• CPC Class Codes: C07D 301/10 : with catalysts containing silver or gold
• CPC Class Codes: C07D 301/22 : by oxidation of saturated compounds with air or molecular oxygen of mixtures of unsaturated and saturated compounds C07D301/04
• CPC Class Codes: Y02P 20/52 : using catalysts, e.g. selective catalysts

Abstract

A precursor mixture for producing a porous body, wherein the precursor mixture comprises: (i) milled alpha alumina powder having a particle size of 0.1 to 6 microns, (ii) boehmite powder that functions as a binder of the alpha alumina powders, and (iii) burnout materials having a particle sizes of 1-10 microns. In some embodiments, an unmilled alpha alumina powder having a particle size of 10 to 100 microns is also included in said precursor mixture. Also described herein is a method for producing a porous body in which the above-described precursor mixture is formed to a given shape, and subjected to a heat treatment step in which the formed shape is sintered to produce the porous body.

Claims

1. A precursor mixture for producing a porous body, wherein the precursor mixture comprises:

(i) at least one milled alpha alumina powder having a particle size of 0.1 to 6 microns, (ii) boehmite powder that functions as a binder of the alpha alumina powders, and (iii) at least one burnout material having a particle size of 1-10 microns.

2. The precursor mixture of claim 1, further comprising unmilled alpha alumina powder having a particle size of 10 to 100 microns.

3. The precursor mixture of claim 2, wherein the weight ratio of milled to unmilled alpha alumina powder is in a range of 0.25:

1 to about 5;

1.

4. The precursor mixture of claim 1, wherein unmilled alpha alumina powder is excluded from the precursor mixture.

5. The precursor mixture of claim 1, further comprising an additive selected from solvents and lubricants.

6. The precursor mixture of claim 1, wherein said burnout material is selected from at least one of a polyolefin powder and graphite powder.

7. The precursor mixture of claim 1, wherein said burnout material is selected from both a polyolefin powder and graphite powder.

8. The precursor mixture of claim 7, wherein the weight ratio of polyolefin powder to graphite powder is in a range of 0.25:

1 to about 5;

1.

9. The precursor mixture of claim 1, wherein the boehmite is present in an amount of at least 10% by weight of total alumina content.

10. The precursor mixture of claim 1, wherein the boehmite is present in an amount of at least 25% by weight of total alumina content.

11. The precursor mixture of claim 1, wherein the boehmite is nano-sized powder with dispersed particle size <

100 nm.

12. The precursor mixture of claim 1, wherein said milled alpha alumina powder has a particle/crystallite size of 0.25-4 microns.

13. The precursor mixture of claim 1, wherein a silicon-containing substance is substantially excluded from the precursor mixture.

14. The precursor mixture of claim 1, wherein a sodium-containing substance is substantially excluded from the precursor mixture.

15. A method for producing a porous body, the method comprising:

providing a precursor mixture comprising (i) milled alpha alumina powder having a particle size of 0.1 to 6 microns, (ii) boehmite powder that functions as a binder of the alpha alumina powders, and (iii) burnout material having a particle size of 1-10 microns;

forming a predetermined shape; and

subjecting the shape to a heat treatment step in which the shape is sintered to produce the porous body.

16. The method of claim 15, further comprising unmilled alpha alumina powder having a particle size of 10 to 100 microns in said precursor mixture.

17. The method of claim 16, wherein the weight ratio of milled to unmilled alpha alumina powder is in a range of 0.25:

1 to about 5;

1.

18. The method of claim 15, wherein unmilled alpha alumina powder is excluded from the precursor mixture.

19. The method of claim 15, wherein the method comprises:

(i) dispersing boehmite into water to produce a dispersion of boehmite;

(ii) adding a milled alpha alumina powder having a particle size of 0.1 to 6 microns to the dispersion of boehmite, and mixing until a first homogeneous mixture is obtained, wherein said boehmite functions as a binder of the alpha alumina powder;

(iii) adding burnout materials having a particle size of 1-10 microns, and mixing until a second homogeneous mixture is obtained;

(iv) forming the second homogeneous mixture to form a shape of said second homogeneous mixture; and

(v) subjecting the formed shape to a heat treatment step in which the formed shape is sintered to produce the porous body.

20. The method of claim 15, wherein said heat treatment step comprises:

(a) subjecting the formed shape to a heat treatment step within a temperature in a range of 35-900°

C. to remove water and burn out the burnout material to produce a pre-fired porous body; and

(b) subjecting the pre-fired porous body to a sintering step at a temperature within a range of 900-2000°

C. to produce said porous body.

21. The method of claim 15, wherein said porous body possesses at least one of a water absorption of at least 30%, a crush strength of at least 40 N, and a BET surface area of at least 0.3 m²/g.

22. The method of claim 15, wherein said porous body possesses a pore architecture that provides at least one of a tortuosity of 7 or less, a constriction of 4 or less, and a permeability of 30 mdarcys or greater.

23. The method of claim 15, wherein said burnout material is selected from a polyolefin powder and graphite powder.

24. The method of claim 19, wherein said burnout material comprises a polyolefin powder, and said step (iii) comprises adding said polyolefin powder having a particle size of 1-10 microns, and mixing until a second homogeneous mixture is obtained.

25. The method of claim 24, wherein said step (iii) further comprises, either simultaneous or subsequent to adding and mixing the polyolefin powder, adding graphite powder as an additional burnout material, and mixing until said second homogeneous mixture is obtained, which includes the graphite powder.

26. The method of claim 25, wherein the weight ratio of polyolefin powder to graphite powder is in a range of 0.25:

1 to about 5;

1.

27. The method of claim 25, wherein said graphite powder has a particle size of 3-10 microns.

28. The method of claim 19, wherein said step (ii) includes, either simultaneous or subsequent to adding and mixing the milled alpha alumina powder, adding unmilled alpha alumina powder having a particle size in a range of 10-100 microns, and mixing until said first homogeneous mixture is obtained.

29. The method of claim 28, wherein the weight ratio of milled to unmilled alpha alumina powder is in a range of 0.25:

1 to about 5;

1.

30. The method of claim 15, wherein the boehmite is present in an amount of at least 10% by weight of total alumina content.

31. The method of claim 15, wherein the boehmite is present in an amount of at least 25% by weight of total alumina content.

32. The method of claim 15, wherein the boehmite is nano-sized powder with dispersed particle size <

100 nm.

33. The method of claim 15, wherein unmilled alpha alumina powder is excluded from the method to produce the porous body.

34. The method of claim 15, wherein a silicon-containing substance is substantially excluded from the method to produce the porous body.

35. The method of claim 15, wherein a sodium-containing substance is substantially excluded from the precursor mixture.

36. The method of claim 15, wherein, after said heat treatment step to form a porous body, said method further comprises depositing silver on and/or in said porous body.

37. The method of claim 15, wherein said milled alpha alumina powder has a particle size of 0.25-4 microns.

38. The method of claim 15, wherein the precursor mixture is formed by one of extrusion or pressing.