Systems and methods for using a boehmite bond-coat with polyimide membranes for gas separation
The subject matter disclosed herein relates to gas separation membranes and, more specifically, to polyimide gas separation membranes. In an embodiment, a gas separation membrane includes a porous substrate, a substantially continuous polyimide membrane layer, and one or more layers of boehmite nanoparticles disposed between the porous substrate and the polyimide membrane layer to form a bond-coat layer. The bond-coat layer is configured to improve the adhesion of the polyimide membrane layer to the porous substrate, and the polyimide membrane layer has a thickness approximately 100 nm or less.
1. A gas separation membrane comprising:
a porous substrate;
a substantially continuous polyimide membrane layer; and
one or more layers of boehmite nanoparticles disposed between the porous substrate and the polyimide membrane layer to form a bond-coat layer, wherein the polyimide membrane layer has a thickness approximately 100 nm or less.
2. The gas separation membrane of claim 1 , wherein the bond-coat layer is configured to improve the adhesion of the polyimide membrane layer to the porous substrate.
3. The gas separation membrane of claim 1 , wherein the boehmite nanoparticles are substantially between approximately 40 nm and 60 nm in diameter.
4. The gas separation membrane of claim 1 , wherein the one or more layers of boehmite nanoparticles form a contiguous bond-coat layer on the porous substrate.
5. The gas separation membrane of claim 1 , wherein the polyimide membrane layer has a thickness between approximately 20 nm and 100 nm.
6. The gas separation membrane of claim 1 , wherein the gas separation membrane has a hydrogen to carbon dioxide selectivity ratio greater than approximately 4.7 and a hydrogen permeance greater than approximately 10 GPU.
7. The gas separation membrane of claim 1 , wherein the gas separation membrane has a hydrogen permeance greater than approximately 350 GPU at 250° C.
8. The gas separation membrane of claim 1 , wherein the gas separation membrane has a hydrogen to carbon dioxide selectivity ratio greater than approximately 5.
9. A method of manufacturing a gas separation membrane comprising:
depositing one or more layers of boehmite nanoparticles onto a porous support structure to form a bond-coat layer; and
depositing a polyimide precursor onto the bond-coat layer; and
performing a thermal treatment of the bond-coat layer and the polyimide precursor at approximately 300° C. or less to form a polyimide membrane layer, wherein the polyimide membrane layer has a thickness approximately 150 nm or less.
10. The method of claim 9 , wherein the support structure comprises a porous ceramic or metallic substrate having a pore size less than approximately 40 nm.
11. The method of claim 9 , wherein the one or more layers of boehmite particles are deposited on the porous support structure using a wet processing method comprising spin-coating, dip-coating, or spray-coating.
12. The method of claim 9 , wherein the bond-coat layer has a thickness between approximately 50 nm and 400 nm.
13. The method of claim 9 , wherein the thermal treatment of the bond-coat layer and the polyimide precursor to form the polyimide membrane layer is performed between approximately 200° C. and 300° C.
14. The method of claim 9 , wherein the polyimide layer has a thickness between approximately 20 nm and 100 nm.
15. The method of claim 9 , wherein the polyimide precursor comprises a polyamic acid solution.
16. The method of claim 15 , wherein the polyimide precursor is deposited on the porous support structure using a wet processing method comprising spin-coating, dip-coating, or spray-coating of the polyamic acid solution.
17. A membrane for gas separation comprising:
a support layer;
an intermediate layer disposed on top of the support layer and providing a surface having a pore size less than approximately 40 nm and having a thickness between approximately 50 and 400 nm;
a bond-coat layer comprising boehmite nanoparticles disposed on top of the intermediate layer and having a thickness between approximately 50 nm and 400 nm; and
a polyimide membrane layer disposed on top of the bond-coat layer having a thickness between approximately 20 and 150 nm.
18. The membrane of claim 17 , wherein the support layer comprises a porous ceramic or metallic substrate having a pore size greater than approximately 30 nm.
19. The membrane of claim 17 , wherein the support layer, the intermediate layer, or both, comprise alumina or silica.
20. The membrane of claim 17 , wherein the membrane has a hydrogen permeance greater than 350 GPU at 250° C.
21. The membrane of claim 17 , wherein the bond-coat layer enhances the adhesion between the polyimide membrane layer and the intermediate layer.