# US 5,700,436 A · Purification of air in enclosed spaces

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- Number: US 5,700,436 A
- Document ID: US5700436A
- Status: Granted
- Kind: A
- Application number: 08/252,699
- Filed: 1994-06-02
- Granted: 1997-12-23
- Earliest claimed: 1993-01-21
- Assignees: Calgon Carbon Corporation
- Inventors: David T. Doughty; Richard A. Hayden; John W. Cobes, III; Thomas M. Matviya
- Web page: https://patentgrep.com/patent/US5700436A

## CPC

- B01D 53/02: by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)}
- B01D 53/04: with stationary adsorbents {(B01D53/025 takes precedence)}
- B01D 53/8609: {Sulfur oxides}
- B01J 20/20: comprising free carbon; comprising carbon obtained by carbonising processes
- B01J 21/18: Carbon
- B01J 37/084: {Decomposition of carbon-containing compounds into carbon}
- C01B 32/336: characterised by gaseous activating agents
- B01D 2253/102: Carbon
- B01D 2257/302: Sulfur oxides
- B01D 2257/304: Hydrogen sulfide
- B01D 2257/306: Organic sulfur compounds, e.g. mercaptans
- B01D 2257/40: Nitrogen compounds
- B01D 2257/404: Nitrogen oxides other than dinitrogen oxide
- B01D 2257/7022: Aliphatic hydrocarbons
- B01D 2257/7027: Aromatic hydrocarbons
- B01D 2259/4508: for cleaning air in buildings
- B01D 2259/4566: for use in transportation means
- B01D 2259/4575: in aeroplanes or space ships
- Y02C 20/10: of nitrous oxide (N2O)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

The present invention discloses an improved method for filtration of air within enclosed spaces. Improvement is achieved by the use of a high-temperature carbonaceous char that is catalytically active for the removal of certain undesirable constituents from contaminated air under ambient temperature conditions. This carbonaceous char is used as an air filtration medium and incorporated into an air filtration device by any of a number of technologies. Such devices may be used for removal of contaminants such as NO.sub.x, NO.sub.2, SO.sub.x, SO.sub.2, H.sub.2 S, mercaptans, light aliphatic gases such as butane and propane and other compounds such as benzene, hexane, toluene, xylene, amines and the like from enclosed or confined structures such as buildings or vehicles including automobiles, aircraft, trucks, farm equipment, and the like.

## Claims

### Claim 1

A method for removing various impurities from contaminated air within confined spaces, said method comprising passing said air through a filtration media comprising a carbonaceous char, said char being prepared by:
a) carbonizing a bituminous material at temperatures below 700.degree. C. in the presence of an oxidant;
b) oxidizing said bituminous material at temperatures below 700.degree. C. during or after said carbonization;
c) contacting said carbonized and oxidized bituminous material at temperatures less than 700.degree. C. with a nitrogen-containing compound, said nitrogen-containing compound being selected from the group consisting of urea and nitrogen containing compounds having at least one nitrogen functionality in which the nitrogen exhibits a formal oxidation number less than that of elemental nitrogen, and during or after said contacting, increasing the temperature to at least 700.degree. C.; and
d) activating said carbonaceous char contacted with said nitrogen-containing compound using any one of H.sub.2 O or CO.sub.2, or combinations thereof, with or without the addition of air, at temperatures above 700.degree. C.

### Claim 2 (depends on 1)

A method as set forth in claim 1 wherein a portion of said air passed through said filtration media is circulated therethrough at least a second time.

### Claim 3 (depends on 1)

A method as set forth in claim 1 wherein said impurities are selected from a group consisting of NO.sub.x, NO.sub.2, SO.sub.x, SO.sub.2, H.sub.2 S, toluene, hexane, butane, propane, benzene, and xylene.

### Claim 4 (depends on 1)

A method as set forth in claim 1 wherein said confined space is the passenger compartment of a vehicle.

### Claim 5 (depends on 1)

A method as set forth in claim 1 including the step of maintaining said filtration media at or near ambient temperature.

### Claim 6

A filter for removing various impurities from contaminated air within confined spaces, said filter having incorporated therein a filtration media comprising a carbonaceous char, said char being prepared by:
a) carbonizing a bituminous material at temperatures below 700.degree. C. in the presence of an oxidant;
b) oxidizing said bituminous material at temperatures below 700.degree. C. during or after said carbonization;
c) contacting said carbonized and oxidized bituminous material at temperatures less than 700.degree. C. with a nitrogen-containing compound, said nitrogen-containing compound being selected from the group comprised of ammonia, urea, melamine, or any derivative thereof having at least one nitrogen functionality in which the nitrogen exhibits a formal oxidation number less than that of elemental nitrogen, and during or after said contacting, increasing the temperature to at least 700.degree. C. and
d) activating said carbonaceous char contacted with said nitrogen-containing compound with any one of H.sub.2 O, CO.sub.2, O.sub.2 or combinations thereof at temperatures above 700.degree. C.

### Claim 7 (depends on 6)

A filter as set forth in claim 6 wherein said carbonaceous char is granular, pelleted, extruded, shaped, formed, or powdered.

### Claim 8 (depends on 6)

A filter as set forth in claim 6 wherein said carbonaceous char is made into a self-supporting unit by any of binding, molding, extrusion or agglomeration.