Mesoporous silica membrane on polymeric hollow fibers
A gas separation device comprising a porous support structure comprising polymeric hollow fibers, and an inorganic mesoporous membrane disposed on the porous support structure is disclosed. The inorganic mesoporous membrane is uniform and free of defects. Further, the inorganic mesoporous membrane comprises a network of interconnected three-dimensional pores that interconnect with the porous support structure. The gas permeances of the inorganic mesoporous membrane is substantially higher than the gas permeances of the polymeric hollow fibers. A method of fabricating the gas separation device is also disclosed.
1. A gas separation device comprising:
a porous support structure comprising polymeric hollow fibers; and
an inorganic mesoporous membrane disposed on the porous support structure, wherein the inorganic mesoporous membrane is uniform and free of defects, wherein the inorganic mesoporous membrane comprises a network of interconnected three-dimensional pores that interconnect with the porous support structure, and wherein the gas permeances of the inorganic mesoporous membrane are substantially higher than the gas permeances of the polymeric hollow fibers.
2. The gas separation device of claim 1 , wherein the inorganic mesoporous membrane comprises a mesoporous Mobil Composition Matter (MCM).
3. The gas separation device of claim 2 , wherein the mesoporous MCM is silica-based.
4. The gas separation device of claim 3 , wherein the mesoporous MCM comprises MCM-48.
5. The gas separation device of claim 4 , wherein the pores range between 1 nm to 5 nm in diameter.
6. The gas separation device of claim 5 , wherein the pores range between 2 nm to 4 nm in diameter.
7. The gas separation device of claim 6 , wherein the pores are about 3 nm in diameter.
8. The gas separation device of claim 1 , wherein the inorganic material comprises a composite mesoporous material, the composite mesoporous material comprising a mesoporous MCM and molecules with functional groups comprising amine groups, quaternary amine groups, thiol groups, carboxyl groups, cyano groups, amide groups, and carbonyl groups.
9. The gas separation device of claim 8 , wherein the quaternary amine is cetyl trimethylammonium bromide (CTAB).
10. The gas separation device of claim 8 , wherein the mesoporous MCM comprises MCM-48.
11. The gas separation device of claim 8 , wherein the mesoporous MCM comprises a mesoporous structure having a network of three-dimensional pores, and the quaternary amine is disposed in the pores of the mesoporous MCM.
12. A method for fabricating the gas separation device of claim 1 , the method comprising:
a) preparing a coating solution, wherein the coating solution comprises a mixture of silica source, a quaternary ammonium surfactant, and acidic water;
b) providing polymeric hollow fibers;
c) immersing at least a portion of the polymeric hollow fibers in the coating solution, thereby forming a wet mesoporous silica membrane on the polymeric hollow fibers;
d) rinsing and drying the wet mesoporous silica membrane on the polymeric hollow fibers, thereby forming a dried mesoporous silica membrane on the polymeric hollow fiber;
e) aging the dried mesoporous silica membrane by exposure to a vapor source of silica;
f) extracting the surfactant from the mesoporous coating by treatment with an appropriate solvent; and
g) infiltrating of polysilsesquioxane (POSS™) molecules into the mesopores to impart selectivity for CO 2 .
13. The method of claim 12 , wherein the quaternary ammonium surfactant comprises CTAB, and further wherein the coating solution comprises 1.0 R:a CTAB:b H 2 O, wherein R is the source of silica, a is between 0.1 and 1, and b is between 20 and 200.
14. The method of claim 12 , wherein the preparing comprises adding acid species to the solution such that the pH of the prepared solution is substantially between 0 and 4.
15. The method of claim 12 , wherein the immersing comprises immersing the polymeric hollow fibers in the coating solution for a period between 10 minutes and 24 hours.
16. The method of claim 12 , wherein the aging comprises aging the dried mesoporous silica membrane at a temperature substantially between 50° C. and 150° C.
17. The method of claim 12 , wherein the aging comprises aging the dried mesoporous silica membrane for a period between 1 hour and 48 hours.
18. The method of claim 12 , wherein the aging comprises exposing the dried mesoporous silica membrane to saturated alkoxysilane vapor.
19. The method of claim 12 , wherein the coating solution further comprises CTAB, and the method further comprises:
extracting the CTAB from the aged mesoporous silica membrane with an extraction solvent; and
rinsing and drying the substantially CTAB-free, mesoporous silica membrane.
20. The method of claim 19 , wherein the extraction solvent comprises water or alcohol or a mixture thereof.
21. The method of claim 19 , wherein the extracting comprises contacting the aged mesoporous silica membrane with the extraction solvent for a period between 1 hour and 72 hours.
22. The method of claim 19 , wherein the extracting comprises contacting the aged mesoporous silica membrane with the extraction solvent at a temperature between 20° C. and 100° C.
23. The method of claim 19 , wherein the pH of the extraction solvent is substantially between 0 and 7.
24. The method of claim 19 , wherein the mesoporous silica membrane is subsequently functionalized with functional groups comprising amine groups, thiol groups, carboxyl groups, cyano groups, amide groups, and carbonyl groups.