Removal of heavy hydrocarbons from gas mixtures containing heavy hydrocarbons and methane

• US 8,529,662 B2
• Filed: 04/04/2008
• Issued: 09/10/2013
• Est. Priority Date: 05/18/2007
• Status: Active Grant

• Current Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Original Assignee: ExxonMobil Research & Engineering Company (Exxon Mobil Corporation)
• Inventors: Kelley, Bruce T., Northrop, Paul S., Chance, Ronald R., Deckman, Harry W., Corcoran, Edward W. Jr., Thomas, Eugene R.
• Primary Examiner(s): Hopkins, Robert A
• Application Number:
  US12/080,660
• Publication Number:
  US 20080282884A1
• Time in Patent Office: 1,985 Days
• Field of Search: 95/96, 951/48, 961/30
• US Class Current: 95/96
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2253/308 Pore size
• CPC Class Codes: B01D 2253/342 Monoliths
• CPC Class Codes: B01D 2256/24 Hydrocarbons
• CPC Class Codes: B01D 2257/702 Hydrocarbons
• 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: B01D 53/0423 Beds in columns
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: C10L 3/10 Working-up natural gas or synthetic natural gas

Abstract

A process for the separation of one or more heavy hydrocarbon gases from a gas mixture containing heavy hydrocarbon gas components and methane. The process is conducted in swing adsorption apparatus containing adsorbent contactor having a plurality of flow channels and wherein 20 volume percent or less of the open pore volume of the contactors, is in the mesopore and macropore range.

Claims

1. A process for the removing heavy hydrocarbon components from a gas mixture containing both a heavy hydrocarbon components and methane, which process comprises:

a) conducting said gas mixture to a swing adsorption gas separation unit wherein the gas separation unit contains at least one adsorbent contactor comprising a gas inlet and a gas outlet, wherein the gas inlet and the gas outlet are in fluid connection by a plurality of open flow channels, wherein the surfaces of the open flow channels are comprised of an adsorbent material that has a selectivity for said heavy hydrocarbon components over said methane greater than 5, wherein the contactor has less than about 20% of its open pore volume in pores with diameters greater than about 20 angstroms and less than about 1 micron, and wherein at least a portion of said heavy hydrocarbon components is adsorbed into said adsorbent material, thereby resulting in a product stream depleted of said heavy hydrocarbon components;

b) collecting said the product stream;

c) desorbing the adsorbed gases from said adsorbent, thereby resulting in a waste gas stream rich in said heavy hydrocarbon components; and

d) collecting said waste gas stream,

wherein said heavy hydrocarbon components are defined as the total of the hydrocarbon compounds in the gas mixture which contain at least 2 carbon atoms, and the product stream has a wt % of methane greater than the wt % of methane of said gas mixture.

2. The process of claim 1 wherein the adsorbent contactor is comprised of an adsorbent material selected from the group consisting of polymers and structured microporous adsorbents.

3. The process of claim 2 wherein the adsorbent material is comprised of a structured microporous adsorbent selected from zeolites and molecular sieves.

4. The process of claim 3 wherein the structured microporous adsorbent is a molecular sieve selected from the group consisting of carbon molecular sieves, aluminophosphate molecular sieves (ALPOs), and silicoaluminophosphate molecular sieves (SAPOs).

5. The process of claim 3 wherein the structured microporous adsorbent is a zeolite having a pore size between about 5 and 20 Angstroms.

6. The process of claim 5 wherein the zeolite is selected from the group consisting of MFI, faujasite, MCM-41 and Beta.

7. The process of claim 6 wherein the Si to Al ratio of the zeolite is from about 1:

1 to about 1000;

1.

8. The process of claim 1 wherein the adsorbent contactor is comprised of a first adsorption zone comprising a first adsorbent material which is in fluid contact with a second adsorption zone comprising a second adsorbent material, wherein the composition of the first adsorbent material is different from the composition of a second adsorbent material.

9. The process of claim 8 wherein the first adsorbent material has a selectivity for the heavy hydrocarbon components of the gas mixture over methane greater than 5;

the second adsorbent material has a selectivity for a third gas component over methane greater than 5; and

the second adsorbent material has a greater adsorption uptake for the third gas component than the first adsorbent material.

10. The process of claim 9 wherein the third gas component is selected from the group consisting of CO₂, N₂, and H₂S.

11. The process of claim 9 wherein the first adsorbent material is comprised of a structured microporous adsorbent selected from zeolites and molecular sieves.

12. The process of claim 11 wherein the structured microporous adsorbent comprised of a molecular sieve selected from the group consisting of carbon molecular sieves, aluminophosphate molecular sieves (ALPOs), and silicoaluminophosphate molecular sieves (SAPOs).

13. The process of claim 11 wherein the structured microporous adsorbent is comprised of a zeolite having a pore size between about 5 and 20 Angstroms.

14. The process of claim 13 wherein the zeolite is selected from the group consisting of MFI, faujasite, MCM-41 and Beta.

15. The process of claim 8 wherein the second adsorbent material is comprised of an 8-ring zeolite that has a Si to Al ratio of about 1:

1 to about 1000;

1.

16. The process of claim 15 wherein the 8-ring zeolite is selected from DDR, Sigma-1 and ZSM-58.

17. The process of claim 1 wherein the adsorbent contactor has less than about 15% of its open pore volume in pores with diameters greater than about 20 angstroms and less than about 1 micron.

18. The process of claim 1 wherein the adsorbent contactor contains an effective amount of a thermal mass material having a higher capacity for adsorbing heat than the adsorbent material.

19. The process of claim 1 wherein the adsorbent contactor contains both mesopores and macropores and wherein at least some of the mesopores and macropores are occupied with a blocking agent of an effective size that is small enough to fit into a mesopore but too large to fit into a micropore of the adsorbent material.

20. The process of claim 19 wherein the blocking agent is selected from the group consisting of polymers, microporous materials, solid hydrocarbons, and liquids.

21. The process of claim 1 wherein the adsorbent contactor is a parallel channel contactor.

22. The process of claim 21 wherein the adsorbent contactor is comprised of an adsorbent material selected from the group consisting of polymers and structured microporous adsorbents.

23. The process of claim 22 wherein the adsorbent material is comprised of a structured microporous adsorbent selected from zeolites and molecular sieves.

24. The process of claim 23 wherein the structured microporous adsorbent is a molecular sieve selected from the group consisting of carbon molecular sieves, aluminophosphate molecular sieves (ALPOs), and silicoaluminophosphate molecular sieves (SAPOs).

25. The process of claim 23 wherein the structured microporous adsorbent is a zeolite having a pore size between about 5 and 20 Angstroms.

26. The process of claim 25 wherein the zeolite is selected from the group consisting of MFI, faujasite, MCM-41 and Beta.

27. The process of claim 26 wherein the Si to Al ratio of the zeolite is from about 1:

1 to about 1000;

1.

28. The process of claim 21 wherein the adsorbent contactor is comprised of a first adsorption zone comprising a first adsorbent material which is in fluid contact with a second adsorption zone comprising a second adsorbent material, wherein the composition of the first adsorbent material is different from the composition of a second adsorbent material.

29. The process of claim 28 wherein the first adsorbent material has a selectivity for the heavy hydrocarbon components of the gas mixture over methane greater than 5;

the second adsorbent material has a selectivity for a third gas component over methane greater than 5; and

the second adsorbent material has a greater adsorption uptake for the third gas component than the first adsorbent material.

30. The process of claim 29 wherein the third gas component is selected from the group consisting of CO₂, N₂, and H₂S.

31. The process of claim 29 wherein the first adsorbent material is comprised of a structured microporous adsorbent selected from zeolites and molecular sieves.

32. The process of claim 31 wherein the structured microporous adsorbent comprised of a molecular sieve selected from the group consisting of carbon molecular sieves, aluminophosphate molecular sieves (ALPOs), and silicoaluminophosphate molecular sieves (SAPOs).

33. The process of claim 31 wherein the structured microporous adsorbent is comprised of a zeolite having a pore size between about 5 and 20 Angstroms.

34. The process of claim 33 wherein the zeolite is selected from the group consisting of MFI, faujasite, MCM-41 and Beta.

35. The process of claim 28 wherein the second adsorbent material is comprised of an 8-ring zeolite that has a Si to Al ratio of about 1:

1 to about 1000;

1.

36. The process of claim 35 wherein the 8-ring zeolite is selected from DDR, Sigma-1 and ZSM-58.

37. The process of claim 21 wherein the contactor has less than about 15% of its open pore volume in pores with diameters greater than about 20 angstroms and less than about 1 micron.

38. The process of claim 37 wherein the adsorbent contactor contains both mesopores and macropores and wherein at least some of the mesopores and macropores are occupied with a blocking agent of an effective size that is small enough to fit into a mesopore but too large to fit into a micropore of the adsorbent material.

39. The process of claim 38 wherein the blocking agent is selected from the group consisting of polymers, microporous materials, solid hydrocarbons, and liquids.

40. The process of claim 37 wherein the parallel channel contactor is in the form selected from:

a) monolith comprised of a microporous adsorbent;

b) a monolith formed from a non-adsorbent material but whose channels are lined with a microporous adsorbent;

c) an array of hollow fibers comprised of a microporous adsorbent; and

d) laminated sheets having an upper and lower face both of which are comprised of a microporous adsorbent.

41. The process of claim 40 wherein the channel gap of the open flow channels is from about 5 to about 1000 microns.

42. The process of claim 41 wherein the ratio of adsorbent volume to open flow channel volume is from about 0.5:

1 to about 100;

1.