Reverse osmosis membranes and separations

Patent metadata

Field	Value
Publication number	US-10486107-B2
Application number	US-201615347993-A
Country	US
Kind code	B2
Filing date	Nov 10, 2016
Priority date	Nov 13, 2015
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

Asymmetric membrane structures are provided that are suitable for various types of separations, such as separations by reverse osmosis. Methods for making an asymmetric membrane structure are also provided. The membrane structure can include at least one polymer layer. Pyrolysis can be used to convert the polymer layer to a porous carbon structure with a higher ratio of carbon to hydrogen.

First claim

The invention claimed is:

1. A method for separating a feed stream, comprising:
performing a membrane separation on a feed stream comprising a first component and a second component, the first component and the second component comprising a hydrocarbon, a hydrocarbonaceous compound, an inorganic compound, or a combination thereof, the feed stream comprising 5 wt % to 95 wt % of the first component, to form a permeate enriched in the first component and a retentate depleted in the first component,
wherein performing the membrane separation comprises exposing the feed stream to a membrane structure comprising a first membrane layer and a second membrane layer under at least one of reverse osmosis conditions or forward osmosis conditions, the reverse osmosis conditions or forward osmosis conditions comprising a feed pressure of at least 0.2 MPag, the first component being in the liquid phase in the feed and in the permeate for at least one position along the length of the membrane, the first membrane layer having a pore volume of at least 0.2 cm 3 /g of pores with a median pore size of at least 20 nm, the second membrane layer comprising a porous carbon layer having a BET surface area of at least about 100 m 2 /g and having a pore size distribution comprising a smallest substantial pore size peak having a median pore size of about 3.0 Angstroms to about 50 Angstroms.

2. The method of claim 1 , wherein the first membrane layer comprises a porous carbon layer, or wherein the first membrane layer comprises a porous metal structure.

3. The method of claim 1 , wherein the first component comprises sulfuric acid and the second component comprises acid soluble oils, and wherein the smallest substantial pore size peak has a median pore size of about 5.0 Angstroms to about 10 Angstroms.

4. The method of claim 1 , wherein the smallest substantial pore size peak has a median pore size of about 5.8 Angstroms to about 6.8 Angstroms.

5. The method of claim 1 , wherein the second component comprises a homogeneous catalyst, and wherein the wherein the smallest substantial pore size peak has a median pore size of about 4.0 Angstroms to about 7.0 Angstroms.

6. The method of claim 1 , wherein the smallest substantial pore size peak has a median pore size of about 4.5 Angstroms to about 6.1 Angstroms, and a) wherein the first component comprises ethanol, or b) wherein the first component comprises isobutane, or wherein the second component comprises 2,2,4 trimethyl pentane, or a combination thereof.

7. The method of claim 1 , wherein the second component comprises methylmethacrylate, methacrylic acid, or a combination thereof, or wherein the second component comprises a sugar.

8. The method of claim 1 , wherein the smallest substantial pore size peak has a median pore size of about 3.0 Angstroms to about 6.0 Angstroms, and wherein a) the first component is water and the second component is isopropyl alcohol, or b) wherein the first component comprises a C 4 -C 8 paraffin and the second component comprises a C io -C 20 paraffin.

9. The method of claim 1 , wherein the smallest substantial pore size peak has a median pore size of about 3.2 Angstroms to about 4.2 Angstroms, and wherein the first component comprises at least one of ethylene, propylene, and n-butylene, and the second component comprises at least one of ethane, propane, and n-butane.

10. The method of claim 1 , wherein the first component and the second component comprise hydrocarbonaceous compounds, or wherein the first component and the second component comprise hydrocarbon isomers.

11. The method of claim 1 , wherein the substantial pore size peak corresponding to the smallest median pore size has a median pore size when the membrane structure is exposed to a liquid for separation that differs by 10% or less from the median pore size when the membrane structure is not exposed to the liquid for separation.

12. A method for separating a feed stream, comprising:
performing a membrane separation on a feed stream comprising a first component and a second component, the first component and the second component comprising a hydrocarbon, a hydrocarbonaceous compound, or a combination thereof, the feed stream comprising 5 wt % to 95 wt % of the first component, to form a permeate enriched in the first component and a retentate depleted in the first component,
wherein performing the membrane separation comprises exposing the feed stream to a membrane structure comprising a first membrane layer and a second membrane layer under at least one of reverse osmosis and forward osmosis conditions, the reverse osmosis conditions or forward osmosis conditions comprising a feed pressure of at least 0.2 MPag, the first component being in the liquid phase in the feed and in the permeate for at least one position along the length of the membrane, the first membrane layer having a pore volume of at least 0.2 cm 3 /g of pores with a median pore size of at least 20 nm, the first membrane layer comprising a porous carbon layer or comprising a porous metal structure, the second membrane layer of the membrane structure comprising a porous carbon layer having a BET surface area of at least about 300 m 2 /g, the second membrane layer having a pore size distribution comprising a smallest substantial pore size peak having a median pore size of about 5.8 Angstroms to about 6.8 Angstroms.

13. The method of claim 12 , wherein the hydrocarbonaceous stream comprises C 8+ aromatics, the hydrocarbonaceous stream comprising 5 wt % to 95 wt % p-xylene, the first component being p-xylene and the second component being at least one of m-xylene and o-xylene.

14. The method of claim 12 , wherein a size difference between the first component and the second component is about 2.0 Angstroms or less; or wherein a peak width of the smallest substantial pore size peak at half of the peak height is about 75% or less of the size difference between the first component and the second component; or a combination thereof.

15. A method for separating a feed stream, comprising:
performing a membrane separation on a feed stream comprising a first component and a second component, the first component and the second component comprising a hydrocarbon, a hydrocarbonaceous compound, or a combination thereof, the feed stream comprising 5 wt % to 95 wt % of the first component, to form a permeate enriched in the first component and a retentate depleted in the first component,
wherein performing the membrane separation comprises exposing the feed stream to a membrane structure comprising a first membrane layer and a second membrane layer under at least one of reverse osmosis and forward osmosis conditions, the reverse osmosis conditions or forward osmosis conditions comprising a feed pressure of at least 0.2 MPag, the first component being in the liquid phase in the feed and in the permeate for at least one position along the length of the membrane, the first membrane layer having a pore volume of at least 0.2 cm 3 /g of pores with a median pore size of at least 20 nm, the first membrane layer comprising a porous carbon layer or comprising a porous metal structure, the second membrane layer of the membrane structure comprising a porous carbon layer having a BET surface area of at least about 300 m 2 /g, the second membrane layer having a pore size distribution comprising a smallest substantial pore size peak having a median pore size of about 3.0 Angstroms to about 10 Angstroms.

Assignees

• Exxonmobil Res & Eng Co
• Georgia Tech Res Inst

Inventors

• Mccool Benjamin A
• Deckman Harry W
• Lively Ryan P
• Koh Dong-Yeun
• Partridge Randall D

Classifications

• C07C5/2732

  Catalytic processes · CPC title

• C07C7/144

  using membranes, e.g. selective permeation · CPC title

• B01D2323/30

  Cross-linking · CPC title

• C07C7/14

  by crystallisation; Purification or separation of the crystals · CPC title

• C07C7/005

  Processes comprising at least two steps in series · CPC title