Pore Size Reduction and Performance Upgrade of Silica Membranes with an Ambient Temperature C-ALD Post-Treatment Method

Abstract

An ambient temperature C-ALD (with NH₃ as catalyst) method was employed to modify sol-gel silica membranes, in order to reduce their pore size and upgrade their gas separation performance. Membranes were characterized before and after modification in terms of permeance and permselectivity with the use of He and N₂, as gas separation indicators. The application of the proposed method significantly improved the permselectivity of the membranes accompanied with a minor permeance reduction. The process temperature renders it ideal for application in commercial membrane modules which utilize economic, current available, sealing technologies. The performance of the C-ALD modified silica membranes in various gas separation applications was further examined, indicating that they are potential candidates for H₂ separation in various chemical processes. Finally, the stability of the C-ALD modified silica membranes in H₂O was studied, indicating some performance loss during the first hours of the membrane's exposure to a H₂O atmosphere, which nevertheless remained high and steady then on.

Keywords:

• C-ALD method
• membrane modification
• silica membranes

ACKNOWLEDGEMENTS

The authors would like to thank the European Union for the financial support of part of this work through the project RFCR-CT-2006-00003.