Preparation and separation properties of porous norbornane-bridged silica membrane

Bis(trimethoxysilyl)norbornane (BTMSN) bearing a highly rigid norbornane bridge was employed as a new silica membrane precursor. The membrane prepared by subjecting BTMSN to the sol–gel process was examined for gas and water separation, and the results were compared with those of ethylene- and ethenylene-bridged silica membranes reported previously. Interestingly, the gas permeability of the BTMSN silica membrane was higher than that of the ethylene- and ethenylene-bridged silica membranes, whereas the water permeability was rather suppressed. The moderately high H2/SF6 permeance ratio of 1,160 and the NaCl rejection of 95 % (2,000 ppm aqueous NaCl) obtained for the BTMSN silica membrane clearly indicate its potential application to gas and water separation.