IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
|
출원번호 |
US-0001664
(2001-10-23)
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발명자
/ 주소 |
- Tripp, Carl P.
- Kanan, Sofian M.
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출원인 / 주소 |
- University of Maine System Board of Trustees
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대리인 / 주소 |
MacMillan, Sobanski & Todd, LLC
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인용정보 |
피인용 횟수 :
5 인용 특허 :
20 |
초록
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Methods of increasing the relative concentration of a target molecule in a gas stream, so that it can be more easily detected by a semiconducting metal oxide based sensor. A gas stream is passed through an adsorbent, the stream containing molecules of the target molecule in a mixture containing mole
Methods of increasing the relative concentration of a target molecule in a gas stream, so that it can be more easily detected by a semiconducting metal oxide based sensor. A gas stream is passed through an adsorbent, the stream containing molecules of the target molecule in a mixture containing molecules of at least one non-target molecule. Both the target and non-target molecules are adsorbed on the adsorbent. Another gas stream containing molecules of a chemical displacer is passed through the adsorbent, the molecules of the chemical displacer adsorbing on the adsorbent to selectively displace the target molecules from the adsorbent while leaving the non-target molecules adsorbed. The chemical displacement causes the displaced target molecules to enter the gas stream. The gas stream can then be passed through a semiconducting metal oxide based sensor to detect the target molecules.
대표청구항
▼
Methods of increasing the relative concentration of a target molecule in a gas stream, so that it can be more easily detected by a semiconducting metal oxide based sensor. A gas stream is passed through an adsorbent, the stream containing molecules of the target molecule in a mixture containing mole
Methods of increasing the relative concentration of a target molecule in a gas stream, so that it can be more easily detected by a semiconducting metal oxide based sensor. A gas stream is passed through an adsorbent, the stream containing molecules of the target molecule in a mixture containing molecules of at least one non-target molecule. Both the target and non-target molecules are adsorbed on the adsorbent. Another gas stream containing molecules of a chemical displacer is passed through the adsorbent, the molecules of the chemical displacer adsorbing on the adsorbent to selectively displace the target molecules from the adsorbent while leaving the non-target molecules adsorbed. The chemical displacement causes the displaced target molecules to enter the gas stream. The gas stream can then be passed through a semiconducting metal oxide based sensor to detect the target molecules. waste stream further containing a portion of said hydrocarbons contained in said feed stream and which have been co-adsorbed on said adsorbent; passing said waste stream to a second adsorption unit containing a hydrocarbon-selective adsorbent so as to preferentially adsorb said co-adsorbed hydrocarbons to produce a second product stream enriched with nitrogen, carbon dioxide or both; and directing a methane-containing stream to said second adsorption unit to purge said hydrocarbon-selective adsorbent and produce a combined stream of methane and said co-adsorbed hydrocarbons adsorbed by said hydrocarbon-selective adsorbent. 2. The process of claim 1, wherein said hydrocarbons contained in said natural gas feed stream comprise C3+hydrocarbons and said hydrocarbons co-adsorbed on said adsorbent comprise C4+hydrocarbons. 3. The process of claim 2, wherein said hydrocarbons co-adsorbed on said adsorbent further include C3hydrocarbons. 4. The process of claim 1, wherein said methane-containing stream used to purge said hydrocarbon-selective adsorbent is obtained from said first pressure swing adsorption unit subsequent to formation of said first product stream, said methane-containing stream having a pressure lower than said first product stream. 5. The process of claim 4, wherein said methane-containing stream for purging said hydrocarbon-selective adsorbent is provided by co-currently depressurizing said first pressure swing adsorption unit to form a methane-containing stream having a pressure lower than said first product stream and a pressure higher than said waste stream. 6. The process of claim 5, wherein said product stream is at a pressure of 100 to 800 psia, said waste stream is at a pressure of less than 10 psia and said methane-containing stream is at a pressure of 20 to 100 psia. 7. The process of claim 5, wherein said adsorbent in said first pressure swing absorption unit is a crystalline titanium silicate molecular sieve. 8. The process of claim 7, wherein said molecular sieve is CTS-1. 9. The process of claim 7, wherein said molecular sieve is barium-ETS-4. 10. The process of claim 5 wherein said adsorbent in said first pressure swing adsorption unit is selective for carbon dioxide. 11. The process of claim 10 wherein said natural gas feed stream contains less than 4 mol. % nitrogen. 12. The process of claim 1, wherein said adsorbent in said first pressure swing adsorption unit is a crystalline titanium silicate molecular sieve. 13. The process of claim 12, wherein said molecular sieve is CTS-1. 14. The process of claim 12, wherein said molecular sieve is barium-ETS-4. 15. The process of claim 1, wherein said hydrocarbon-selective absorbent is an amorphous carbon or silica gel adsorbent. 16. The process of claim 1 wherein said adsorbent in said first pressure swing adsorption unit is selective for carbon dioxide. 17. The process of claim 16 wherein said adsorbent selective for carbon dioxide is a silica gel. 18. The process of claim 16 wherein said adsorbent selective for carbon dioxide is activated carbon. 19. The process of claim 16 wherein said natural gas feed stream contains less than 4 mol. % nitrogen. 20. The process of claim 19 wherein said adsorbent selective for carbon dioxide is a silica gel. 21. The process of claim 1 wherein said first adsorbent in said first pressure swing adsorbent unit contains a mixture of CTS-1 and an equilibrium adsorbent wherein said equilibrium adsorbent has a greater affinity for C3+hydrocarbon over methane. 22. The process of claim 21 where said equilibrium adsorbent is silica gel, ZnX, activated carbon or alumina. 23. The process of claim 1, wherein said first product stream contains over 90 mol. % methane. 24. The process of claim 1, comprising subsequent to forming said combined stream of methane and co-adsorbed hydrocarbons, separating said co-adsorbed hydrocarbons from said combined stream. 25. The process of claim 24, wherein said co-adsorbed hydrocarbons comprise C3+hydrocarbons and separating said C3+hydrocarbons from said combined stream by condensing said C3+hydrocarbons. 26. The process of claim 1, wherein said natural gas feed stream contains 4 to 15 mol. % C3+hydrocarbons. 27. The process of claim 1, wherein said natural gas feed stream contains greater than 4 mol. % nitrogen. 28. A process for the separation of nitrogen, carbon dioxide or both from a natural gas feed stream, and the recovery of C3+hydrocarbons from said feed stream, which comprises: passing said natural gas feed stream to a first pressure swing adsorption unit containing a crystalline titanium silicate, adsorbent so as to preferentially adsorb nitrogen and carbon dioxide and produce a first product stream containing at least 90 mol. % methane and a low pressure waste stream having a higher molar concentration of nitrogen and carbon dioxide than said feed stream, said waste stream further containing a portion of said C3+hydrocarbons contained in said feed stream and which have been co-adsorbed on said titanium silicate adsorbent; passing said waste stream to a second adsorption unit containing a hydrocarbon-selective adsorbent so as to preferentially adsorb said co-adsorbed C3+hydrocarbons to produce a second product stream enriched with nitrogen and carbon dioxide; and directing a methane-containing stream having a pressure intermediate the pressure of said first product stream and said waste stream to said second adsorption unit to purge said hydrocarbon-selective adsorbent and produce a combined stream of methane and said co-adsorbed C3+hydrocarbons adsorbed by said hydrocarbon-selective adsorbent. 29. The process of claim 28 wherein said crystalline titanium silicate is CTS-1 or an alkaline earth-exchanged ETS-4. 30. The process of claim 29 wherein said natural gas feed stream contains greater than 2 mol. % carbon dioxide, said first pressure swing adsorption unit further containing a silica gel carbon dioxide-selective adsorbent. 31. The process of claim 29 wherein said natural gas feed stream contains greater than 2 mol. % carbon dioxide, said first pressure swing adsorption unit further containing an activated carbon or carbon molecular sieve carbon dioxide-selective adsorbent. 32. The process of claim 28 wherein said natural gas feed stream contains greater than 4 mol. % nitrogen. 33. The process of claim 28 wherein said natural gas feed stream contains less than 2 mol. % carbon dioxide. 34. The process of claim 28 wherein said natural gas feed stream contains greater than 2 mol. % carbon dioxide, said first pressure swing adsorption unit further containing a silica gel carbon dioxide-selective adsorbent. 35. The process of claim 28 wherein said natural gas feed stream contains greater than 2 mol. % carbon dioxide, said first pressure swing adsorption unit further containing an activated carbon or carbon molecular sieve carbon dioxide-selective adsorbent. 36. The process of claim 28 wherein said first pressure swing adsorption unit contains an additional adsorbent which has a selectivity for C3+hydrocarbons greater than a selectivity for methane. 37. The process of claim 36 wherein said additional adsorbent is a silica gel, ZnX, activated carbon or alumina. 38. A process for the separation of carbon dioxide from a natural gas feed stream, and the recovery of C3+hydrocarbons from said feed stream, which comprises: passing said natural gas feed stream to a first pressure swing adsorption unit containing a silica gel adsorbent so as to preferentially adsorb carbon dioxide and produce a first product stream containing at least 90 mol. % methane and a low pressure waste stream having a higher molar concentration of carbon dioxide than said feed stream, said waste stream further containing a portion of said C3+hydrocarbons contained in said fe
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