Ozone purification process

• US 6,197,091 B1
• Filed: 03/05/1999
• Issued: 03/06/2001
• Est. Priority Date: 03/05/1999
• Status: Expired due to Fees

• Current Assignee: BOC Group, Inc. (Messer Adolf Family)
• Original Assignee: BOC Group, Inc. (Messer Adolf Family)
• Inventors: Sadkowski, Piotr J., Ji, Wenchang, Ferrell, Robert James
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US09/263,614
• Time in Patent Office: 732 Days
• Field of Search: 95/45, 95/47--55, 95/96, 952/30, 96/4, 96/7--14, 204/176, 422/186.07, 422/186.08, 422/186.11, 422/186.12
• US Class Current: 95/45
• CPC Class Codes: B01D 53/228 characterised by specific membranes
• CPC Class Codes: B01D 53/229 Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• CPC Class Codes: C01B 13/10 Preparation of ozone
• CPC Class Codes: C02F 1/78 with ozone C02F1/4672 takes precedence

Abstract

An ozone-oxygen gas stream produced by passing oxygen into an ozone generator is introduced into a membrane separation unit containing an ozone-permeable membrane. Ozone-enriched gas passes through the membrane and is recovered or it contacts a liquid or gas stream which contains ozone-reactive substances, thereby oxidizing the substances. The oxygen-enriched gas stream produced on the feed side of the membrane by permeation of ozone through the membrane is recycled to the ozone generator. Prior to being recycled, the oxygen-enriched stream may be purified to remove gaseous impurities which permeate through the membrane from the liquid or gas stream being treated.

Claims

1. A process comprising the steps:

(a) passing an oxygen-containing gas through an ozone generator, thereby producing a gaseous product comprising ozone and oxygen;

(b) introducing said gaseous product into the feed zone of gas separation means comprising a feed zone and a permeate zone separated by at least one ozone-permeable membrane, thereby permeating an ozone-enriched stream into said permeate zone and producing an oxygen-enriched stream in said feed zone;

(c) introducing a fluid stream into said permeate zone; and

(d) recycling said oxygen-enriched stream to said ozone generator.

2. The process of claim 1, wherein said oxygen-containing gas is oxygen-enriched air or substantially pure oxygen.

3. The process of claim 1, wherein said oxygen-containing gas is substantially pure oxygen.

4. The process of claim 3, wherein said ozone-permeable membrane comprises polymeric membranes, inorganic membranes, inorganic-organic membranes or combinations thereof.

5. The process of claim 3, wherein said ozone-permeable membrane comprises elastomeric polymers, glassy polymers, ion-exchange resins, zeolites, carbon molecular sieves, metal oxides, zeolite-filled polymers, carbon molecular sieve-filled polymers and combinations thereof.

6. The process of claim 3, wherein said ozone-permeable membrane comprises perfluoro-2,2-dimethyl-1,3-dioxole-tetrafluoroethylene copolymer, tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octene-sulfonic acid copolymer, silicone rubber, silica or combinations thereof.

7. The process of claim 1, wherein said fluid stream contains one or more ozone-reactive substances.

8. The process of claim 7, wherein said one or more ozone-reactive substances comprises hydrogen, carbon monoxide, nitrogen compounds, sulfur compounds, organic compounds, microbiological agents or mixtures thereof.

9. The process of claim 8, wherein said fluid stream is a liquid stream.

10. The process of claim 9, wherein said ozone-enriched stream nondispersively mixes with said liquid stream in said permeate zone.

11. The process of claim 10, wherein said liquid stream is an aqueous stream.

12. The process of claim 11, wherein the total pressure in said permeate zone is at least as great as the total pressure in said feed zone.

13. The process of claim 11, wherein said aqueous stream is drinking water, semiconductor component cleaning liquid or wastewater.

14. The process of claim 9, wherein said membrane is hydrophobic, organophobic or both of these.

15. The process of claim 8, wherein said fluid stream is a gaseous stream.

16. The process of claim 15, wherein the oxygen partial pressure in said permeate zone is maintained at least as great as the oxygen partial pressure in said feed zone.

17. The process of claim 15, wherein said gaseous stream is air, breathable gas or an exhaust gas from a combustion process.

18. The process of claim 8, wherein said one or more ozone-reactive substances comprise said hydrogen, said carbon monoxide, said nitrogen compounds comprise nitrogen oxides, said sulfur compounds comprise sulfur dioxide and hydrogen sulfide, said organic compounds comprise C₁-C₃ hydrocarbons, said microbiological comprise living organisms and viruses or mixtures thereof.

19. The process of claim 7 or claim 15, further comprising the step of removing gaseous impurities from said oxygen-enriched stream prior to step (c).

20. The process of claim 19, wherein said step of removing gaseous impurities from said oxygen-enriched stream comprises drying said oxygen-enriched stream.

21. The process of claim 19, wherein said step of removing gaseous impurities from said oxygen-enriched stream comprises adsorptive separation, membrane separation or combinations thereof.

22. The process of claim 21, wherein said step of removing gaseous impurities from said oxygen-enriched stream comprises adsorptive separation carried out using one or more zeolites, activated carbon, carbon molecular sieves or combinations thereof.