Claims
- 1. A method of removing an alkyl halide from a gas stream, the method comprising contacting the gas stream with a mixture comprising water, a phase transfer catalyst, and a nucleophile.
- 2. The method of claim 1, wherein the mixture consists essentially of water, a phase transfer catalyst, and a nucleophile.
- 3. The method of claim 1, wherein the mixture further comprises an organic solvent capable of diluting the phase transfer catalyst.
- 4. The method of claim 1, wherein the nucleophile comprises nitrogen at the nucleophilic center.
- 5. The method of claim 1, wherein the nucleophile comprises sulfur at the nucleophilic center.
- 6. The method of claim 1, wherein the nucleophile comprises selenium at the nucleophilic center.
- 7. The method of claim 1, wherein the nucleophile comprises an anion selected from the group consisting of cyanide, cyanate, carboxylate, nitrite, azide, sulfate, and carbonate anions, and derivatives thereof.
- 8. The method of claim 1, wherein the nucleophile comprises an alkoxide anion.
- 9. The method of claim 1, wherein the nucleophile comprises an anion selected from the group consisting of sulfide, hydrogen sulfide, thiolate and cyanide, and the alkyl halide comprises methyl bromide.
- 10. The method of claim 1, wherein the nucleophile comprises an aliphatic or aromatic disulfide or polysulfide, or an anion selected from the group consisting of sulfide, hydrogen sulfide, sulfite, hydrogen sulfite, thiocyanate, thiophenoxide anions, polysulfide anions, and derivatives thereof.
- 11. The method of claim 1, wherein the nucleophile comprises an anion selected from the group consisting of sulfide and hydrogen sulfide anions.
- 12. The method of claim 1, wherein the nucleophile comprises an anion selected from the group consisting of alkyl thiolate, aryl thiolate, and aralkyl thiolate.
- 13. The method of claim 1, wherein the nucleophile comprises a primary, secondary, or tertiary alkyl, aryl, or aralkyl amine or phosphine, an alkyl, aryl, or aralkyl sulfide, or a mixture of any of these.
- 14. The method of claim 1, wherein the phase transfer catalyst comprises a tetrasubstituted phosphonium cation, wherein each of the substituents is independently an alkyl, aryl, or aralkyl group.
- 15. The method of claim 1, wherein the phase transfer catalyst comprises a tetrasubstituted ammonium cation, wherein each of the substituents is independently an alkyl, aryl, or aralkyl group.
- 16. The method of claim 1, wherein the phase transfer catalyst comprises a tetrabutylammonium cation.
- 17. The method of claim 1, wherein the phase transfer catalyst comprises a methyltrioctylammonium cation.
- 18. The method of claim 1, wherein the mixture further comprises iodide ion.
- 19. The method of claim 1, wherein the contacting is performed more than once.
- 20. The method of claim 1, wherein the alkyl halide comprises methyl bromide.
- 21. The method of claim 1, wherein the alkyl halide comprises methyl bromide and the nucleophile comprises an anion selected from the group consisting of nitrite, thiosulfate, sulfite, and combinations thereof.
- 22. A method of removing methyl bromide from an air stream, the method comprising contacting the gas stream with a mixture comprising water, a phase transfer catalyst comprising a tetraalkylammonium cation, and a nucleophile comprising at least one of sulfide anion and hydrogen sulfide anion.
- 23. The method of claim 22, in which the phase transfer catalyst comprises methyltrioctylammonium chloride, the nucleophile comprises at least one of sodium sulfide and sodium hydrogen sulfide, and wherein the at least one of sodium sulfide and sodium hydrogen sulfide is dissolved in the water at a concentration of from about 0.1 wt. % to a saturation limit.
- 24. The method of claim 23, in which the concentration is from about 10 wt. % to about 20 wt. %.
- 25. The method of claim 1 in which the phase transfer catalyst is present in a molar amount equal to from 1% to 50% of the moles of nucleophile.
- 26. A method of removing methyl bromide from a gas volume, the method comprising withdrawing a gas stream from the gas volume and contacting the gas stream with a mixture comprising water, a phase transfer catalyst, and a nucleophile, thereby producing a purified gas stream.
- 27. The method of claim 26, wherein the gas volume is an air volume, the gas stream is an air stream, and the purified gas stream is a purified air stream.
- 28. The method of claim 27 further comprising returning the purified air stream to the air volume.
- 29. A system for removing methyl bromide from a gas volume, comprising:
a reactor assembly comprising a reaction vessel containing a mixture comprising water, a phase transfer catalyst, and a nucleophile; and a gas stream feed tube for removing a gas stream from the gas volume and directing it to the reactor assembly; wherein the reactor assembly is adapted to provide contact of the gas stream with the mixture, thereby forming a purified gas stream.
- 30. The system of claim 29, further comprising a purified gas stream return tube adapted to return the purified gas stream to the gas volume.
- 31. The system of claim 29, comprising a plurality of reactor assemblies connected in series.
- 32. The system of claim 29, comprising a plurality of reactor assemblies connected in parallel.
- 33. The system of claim 29, further comprising a pump adapted to cause the gas stream to flow through the reactor assembly.
- 34. The system of claim 29 further comprising a gas disperser adapted to convert the gas stream to small bubbles of gas, thereby providing said contact of the gas stream with the mixture.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation in part of U.S. application Ser. No. 10/236,382, filed Sep. 6, 2002, and claims priority to U.S. Provisional Appl. No. 60/397,433, filed Jul. 19, 2002, both of which are incorporated herein by reference.
Provisional Applications (1)
|
Number |
Date |
Country |
|
60397433 |
Jul 2002 |
US |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
10236382 |
Sep 2002 |
US |
Child |
10446753 |
May 2003 |
US |