Method for producing porous bodies with enhanced properties

Patent metadata

Field	Value
Publication number	US-2016354759-A1
Application number	US-201615171273-A
Country	US
Kind code	A1
Filing date	Jun 2, 2016
Priority date	Jun 2, 2015
Publication date	Dec 8, 2016
Grant date	—

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.

First claim

What is claimed is:

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 m 2 /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.

Assignees

• Scient Design Co

Inventors

• Suchanek Wojciech L
• Julian Matthew

Classifications

• C04B38/00

  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 title

• B01J21/04 Primary

  Alumina · CPC title

• B01J37/0018

  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 title

• C04B41/009

  characterised by the material treated · CPC title

• C04B41/88

  Metals · CPC title