Formation of catalytic regions within porous structures using supercritical phase processing

1. A method of forming a catalytic region on a pre-formed porous structure having an exterior surface and a plurality of pores, the method comprising:

forming a supercritical dispersion, wherein the supercritical dispersion comprises a plurality of particles dispersed in a supercritical fluid;

exposing the pre-formed porous structure to the supercritical dispersion; and

depositing the plurality of particles from the supercritical dispersion onto the porous structure, wherein each one of the deposited plurality of particles is catalytic, thereby forming one or more catalytic regions on the porous structure.

2. The method of claim 1 , wherein the porous structure is a microporous structure.

3. The method of claim 2 , wherein the plurality of pores has an average pore diameter of less than 1 micron.

4. The method of claim 2 , wherein the plurality of pores has an average pore diameter of less than 2 nanometers.

5. The method of claim 2 , wherein the plurality of particles is a nano-powder having an average grain size less than 250 nanometers and an aspect ratio between one and one million.

6. The method of claim 1 , wherein one or more of the catalytic regions is formed to partially or completely surround an interior pore within the porous structure.

7. The method of claim 1 , wherein each one of the plurality of particles is catalytic prior to its deposition onto the porous structure.

8. The method of claim 1 , wherein the step of forming the supercritical dispersion comprises:

dispersing the plurality of particles within a carrier fluid, thereby forming a carrier mixture;

mixing the supercritical fluid with the carrier mixture, thereby forming a heterogeneous mixture; and

removing the carrier fluid from the heterogeneous mixture, thereby forming the supercritical dispersion.

9. The method of claim 8 , wherein the carrier fluid is a surfactant.

10. The method of claim 8 , wherein the carrier fluid comprises a fluid selected from the group consisting of water, oil and alcohol.

11. The method of claim 8 , wherein the step of removing the carrier fluid from the heterogeneous mixture comprises performing reverse osmosis.

12. The method of claim 8 , wherein the step of removing the carrier fluid from the heterogeneous mixture comprises a filtering process.

13. The method of claim 1 , wherein the step of depositing the plurality of particles onto the porous structure comprises removing the supercritical fluid from the supercritical dispersion while the supercritical dispersion is in contact with the porous structure.

14. The method of claim 13 , wherein the step of removing the supercritical fluid from the supercritical dispersion comprises:

exposing the supercritical dispersion to a low-pressure environment; and

venting the supercritical fluid to the low-pressure environment.

15. A method of forming a catalytic region on a pre-formed microporous structure having an exterior surface and a plurality of pores, the method comprising:

dispersing a plurality of particles within a carrier fluid, thereby forming a carrier mixture;

mixing a supercritical fluid with the carrier mixture, thereby forming a heterogeneous mixture;

removing the carrier fluid from the heterogeneous mixture, thereby forming a supercritical dispersion, wherein the supercritical dispersion comprises the plurality of particles dispersed in the supercritical fluid;

exposing the pre-formed microporous structure to the supercritical dispersion; and

removing the supercritical fluid from the supercritical dispersion while the supercritical dispersion is in contact with the porous structure, thereby depositing the plurality of particles from the supercritical dispersion onto the microporous structure, wherein each one of the deposited plurality of particles is catalytic, and the deposition of the particles forms one or more catalytic regions on the microporous structure.

16. The method of claim 15 , wherein the plurality of pores has an average pore diameter of less than 1 micron.

17. The method of claim 15 , wherein the plurality of pores has an average pore diameter of less than 2 nanometers.

18. The method of claim 15 , wherein the plurality of particles is a nano-powder having an average grain size less than 250 nanometers and an aspect ratio between one and one million.

19. The method of claim 15 , wherein one or more of the catalytic regions is formed to partially or completely surround an interior pore within the microporous structure.

20. The method of claim 15 , wherein each one of the plurality of particles is catalytic prior to its deposition onto the porous structure.

21. The method of claim 15 , wherein the carrier fluid is a surfactant.

22. The method of claim 15 , wherein the carrier fluid comprises a fluid selected from the group consisting of water, oil and alcohol.

23. The method of claim 15 , wherein the step of removing the carrier fluid from the heterogeneous mixture comprises performing reverse osmosis.

24. The method of claim 15 , wherein the step of removing the carrier fluid from the heterogeneous mixture comprises a filtering process.

25. The method of claim 15 , wherein the step of removing the supercritical fluid from the supercritical dispersion comprises:

exposing the supercritical dispersion to a low-pressure environment; and

venting the supercritical fluid to the low-pressure environment.