Abstract
Nanoporous silica composite membranes for gas separation have been synthesized by the organic‐templating sol‐gel technique and their CO2/N2 separation efficiency has been investigated. Stable organic‐templating silica sols capable of coating nanoporous amorphous silica layers on SiO2/α‐Al2O3 composite supports were prepared by the two‐step acid‐catalytic process using the mixture of TEOS and template such as MTES (methyltriethoxysilane) being covalently bonded with TEOS or TPABr (tetrapropylammonium bromide) non‐reacted. The SiO2/α‐Al2O3 composite supports (pore size 1.6 nm) prepared by pressurized coating of the porous α‐alumina tube with a nanoparticulate silica sol were found to be more suitable than pure α‐Al2O3 composite supports for synthesizing crack‐free membranes which have the high CO2/N2 separation efficiency. The N2 permeability of organic‐templated silica composite membranes synthesized was about 10−8 mol/m2 · s · Pa and the CO2/N2 separation factor of the MTES‐templated silica composite membranes was enhanced up to 19 at room temperature by surface‐modifying the templated silica membrane with the TEOS‐EtOH solution.
Acknowledgment
This work was supported by grant No. R01‐1999‐000‐00198‐0 from the Basic Research Program of the Korea Science & Engineering Foundation.