Broad spectrum filter system for filtering contaminants from air or other gases

• US 6,344,071 B1
• Filed: 05/22/2000
• Issued: 02/05/2002
• Est. Priority Date: 05/22/2000
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Smith, Simon J., Hern, Jamie A.
• Primary Examiner(s): Hopkins, Robert A.
• Application Number:
  US09/576,406
• Time in Patent Office: 624 Days
• Field of Search: 554/86, 555/24, 555/18, 555/19, 555/12, 961/21, 961/31, 961/32, 951/41, 951/42, 502/401
• US Class Current: 95/274
• CPC Class Codes: B01D 53/02 by adsorption, e.g. preparative gas chromatography solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01
• CPC Class Codes: B01J 20/0218 Compounds of Cr, Mo, W
• CPC Class Codes: B01J 20/0233 Compounds of Cu, Ag, Au
• CPC Class Codes: B01J 20/0237 Compounds of Cu
• CPC Class Codes: B01J 20/0244 Compounds of Zn
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 20/28004 Sorbent size or size distribution, e.g. particle size
• CPC Class Codes: B01J 20/28016 Particle form
• CPC Class Codes: B01J 20/2805 Sorbents inside a permeable or porous casing, e.g. inside a container, bag or membrane
• CPC Class Codes: B01J 20/28052 Several layers of identical or different sorbents stacked in a housing, e.g. in a column
• CPC Class Codes: B01J 20/3092 Packing of a container, e.g. packing a cartridge or column of chromatography columns B01D15/206
• CPC Class Codes: B01J 20/3204 Inorganic carriers, supports or substrates
• CPC Class Codes: B01J 20/3236 containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
• CPC Class Codes: B01J 20/3255 comprising a cyclic structure containing at least one of the heteroatoms nitrogen, oxygen or sulfur, e.g. heterocyclic or heteroaromatic structures
• CPC Class Codes: B01J 20/3289 Coatings involving more than one layer of same or different nature
• CPC Class Codes: B01J 2220/42 Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: B01J 2220/485 Plants or land vegetals, e.g. cereals, wheat, corn, rice, sphagnum, peat moss
• CPC Class Codes: B01J 2220/56 Use in the form of a bed

Abstract

Filter medium includes at least two kinds of filter media particles. A first plurality of filter media particles includes an extended surface area substrate comprising at least one transition metal impregnant. A second plurality of filter media particles includes an extended surface area substrate comprising a tertiary amine impregnant. In preferred embodiments, at least one and preferably both of the kinds of filter media particles is/are substantially free of chromium, and more preferably contain no detectable chromium. The filtering medium has very broad filtering capabilities. The filtering medium successfully achieves performance levels mandated both by applicable industrial filter approval specifications and by international military filter performance specifications.

Claims

1. A filter medium, comprising:

a first plurality of filter media particles, comprising an extended surface area substrate comprising at least one transition metal impregnant; and

a second plurality of filter media particles, comprising an extended surface area substrate comprising an amine impregnant.

2. The filter medium of claim 1, wherein at least one of the first and second plurality of filter media particles is substantially free of chromium.

3. The filter medium of claim 1, wherein each of the first and second plurality of filter media particles is substantially free of chromium.

4. The filter medium of claim 1, wherein the first and second plurality of filter media particles are intermixed.

5. The filter medium of claim 1, wherein the filter medium comprises first and second filter media layers;

the first plurality of filter media particles is positioned in the first filter media layer; and

the second plurality of filter media particles is positioned in the second filter media layer.

6. The filter medium of claim 1, wherein the amine impregnant comprises TEDA.

7. The filter medium of claim 6, wherein the second plurality of filter media particles comprise 0.1 to 10 weight percent of TEDA.

8. The filter medium of claim 6, wherein the second plurality of filter media particles further comprises Cu, Ag, Zn, and Mo impregnants.

9. The filter medium of claim 6, wherein the second plurality of filter media particles is substantially free of transition metal impregnants.

10. The filter medium of claim 6 wherein the second plurality of filter media particles further comprises Cu, Zn, Mo, ammonium salt, and sulfate salt impregnants.

11. The filter medium of claim 10 wherein the second plurality of filter media particles further comprises up to about 15 weight percent moisture.

12. The filter medium of claim 6, wherein the second plurality of filter media particles further comprises up to about 15 weight percent moisture.

13. The filter medium of claim 8, wherein the first plurality of filter media particles comprises a Zn salt impregnant.

14. The filter medium of claim 10 wherein the first plurality of filter media particles comprises Cu, Zn, and Mo impregnants.

15. The filter medium of claim 1, wherein the first plurality of filter media particles comprises a Zn impregnant, and wherein the second plurality of filter media particles comprises TEDA and Cu, Ag, Zn, and Mo impregnants.

16. The filter medium of claim 1, wherein the first plurality of filter media particles comprises Cu, Zn, and Mo impregnants, and wherein the second plurality of filter media particles comprises TEDA and is at least substantially free of transition metal impregnants.

17. A method of making a filter medium, comprising the steps of:

(a) providing a first plurality of filter media particles, comprising an extended surface area substrate comprising at least one transition metal impregnant, said first plurality of particles being substantially free of a tertiary amine impregnant;

(b) providing a second plurality of filter media particles, comprising an extended surface area substrate comprising a tertiary amine impregnant; and

(c) incorporating the first and second pluralities of filter media particles into at least one filter bed of the filter medium.

18. The method of claim 17, wherein step (c) comprises incorporating the first and second pluralities of filter media particles into a filter bed in which said pluralities are intermixed.

19. The method of claim 17, wherein step (c) comprises incorporating the first plurality of filter media particles into a first filter bed and incorporating the second plurality of filter media particles into a second filter bed.

20. The method of claim 19, wherein the filter medium has an inlet through which a gas enters the filter medium, and outlet through which the gas exits the filter medium, and wherein the first filter bed is proximal to the inlet and the second filter bed is proximal to the outlet.

21. The method of claim 17, wherein at least one of the first and second plurality of filter media particles is substantially free of chromium.

22. The method of claim 17, wherein each of the first and second plurality of filter media particles is substantially free of chromium.

23. The method of claim 17, wherein the amine impregnant comprises TEDA.

24. The method of claim 23, wherein the second plurality of filter media particles further comprises Cu, Ag, Zn, and Mo impregnants.

25. The method of claim 23, wherein the second plurality of filter media particles is substantially free of transition metal impregnants.

26. The method of claim 17, wherein the second plurality of filter media particles further comprises up to about 15 weight percent moisture.

27. The method of claim 23, wherein the second plurality of filter media particles further comprises up to about 15 weight percent moisture.

28. The method of claim 24, wherein the first plurality of filter media particles comprises a Zn salt impregnant.

29. The method of claim 17, wherein the first plurality of filter media particles comprises a Zn impregnant, and wherein the second plurality of filter media particles comprises TEDA and Cu, Ag, Zn, and Mo impregnants.

30. The method of claim 17, wherein the first plurality of filter media particles comprises Cu, Zn, and Mo impregnants, and wherein the second plurality of filter media particles comprises TEDA and is at least substantially free of transition metal impregnants.

31. A method of filtering contaminants from a gas, comprising the step of causing the gas to flow through a filter medium incorporating

(a) a first plurality of filter media particles, comprising an extended surface area substrate comprising at least one transition metal impregnant;

and

(b) a second plurality of filter media particles, comprising an extended surface area substrate comprising an amine impregnant.

32. The method of claim 31, wherein step (c) comprises incorporating the first and second pluralities of filter media particles into a filter bed in which said pluralities are intermixed.

33. The method of claim 31, wherein step (c) comprises incorporating the first plurality of filter media particles into a first filter bed and incorporating the second plurality of filter media particles into a second filter bed.

34. The method of claim 33, wherein the filter medium has an inlet through which a gas enters the filter medium, and outlet through which the gas exits the filter medium;

and wherein the first filter bed is proximal to the inlet and the second filter bed is proximal to the outlet.

35. The method of claim 31, wherein at least one of the first and second plurality of filter media particles is substantially free of chromium.

36. The method of claim 31, wherein each of the first and second plurality of filter media particles is substantially free of chromium.

37. The method of claim 31, wherein the amine impregnant comprises TEDA.

38. The method of claim 37, wherein the second plurality of filter media particles further comprises Cu, Ag, Zn, and Mo impregnants.

39. The method of claim 37, wherein the second plurality of filter media particles is substantially free of transition metal impregnants.

40. The method of claim 31, wherein the second plurality of filter media particles further comprises up to about 15 weight percent moisture.

41. The method of claim 37, wherein the second plurality of filter media particles further comprises up to about 15 weight percent moisture.

42. The method of claim 38, wherein the first plurality of filter media particles comprises a Zn salt impregnant.

43. The method of claim 31, wherein the first plurality of filter media particles comprises a Zn impregnant, and wherein the second plurality of filter media particles comprises TEDA and Cu, Ag, Zn, and Mo impregnants.

44. The method of claim 31, wherein the first plurality of filter media particles comprises Cu, Zn, and Mo impregnants, and wherein the second plurality of filter media particles comprises TEDA and is at least substantially free of transition metal impregnants.