SYNTHESIS OF HYDROPHOBIC SILICA MEMBRANE SYSTEM FOR SEPARATION OF H2/C02 MIXTURE

Membrane separation technology has attracted much increasing interest recently due
to their good gas separation properties and energy efficiency as compared to the other
separation technologies, such as cryogenic distillation and pressure swing adsorption.
Many efforts have been made to develop membranes for separation of H2/C02
mixture to obtain high purity H2 for various applications. Most currently investigated
membranes for H2 separation are polymer and metallic such as palladium based
membranes. However, they suffer from limited stability under harsh circumstances
such as high temperatures, typically for many H2 process streams. Inorganic porous
silica membranes are therefore highly promising for high temperature H2 separation
because of their high thermal and chemical stabilities. Currently sol-gel derived
tetraethoxyorthosilane (TEOS) based porous silica membranes are attractive
technologies for selective removal of hydrogen with pore size smaller than I nm in a
wide range of temperature up to I 000 ·c were found to show some excellent
separation performance for hydrogen in dry conditions in a wide temperature range,
5~00 ·c. But the major concern is their ability to absorb moisture from the air
(hydrophilic in nature) at room temperature and absorption of moisture from process
stream at higher temperature, which effect separation process due to pore blocking
and structural changes in membrane. In order to reduce the interaction of water and
retaining the pore structure, development of hydrophobic silica membrane was
important to solve this challenge.