SEPARATION OF GASEOUS-MIXTURES OF CO2 AND CH4 USING A COMPOSITE MICROPOROUS GLASS MEMBRANE ON CERAMIC TUBING

Separation of a gaseous mixture of CO2 and CH4 was carried out using a microporous, thin glass membrane coated on the surface of a porous ceramic tubing. The glass membrane was prepared by repeating the following procedure: dipping the ceramic tubing into a metal alkoxide solution containing B2O3, followed by drying, heating and leaching in HCl solution. The thickness of the membrane was in the range of 5-23 μm, depending upon the number of dips. The structure of the membrane was investigated by means of a scanning electron microscope. The mean pore diameter estimated was in the range of 4-64 nm. The maximum separation factor of 1.48 was obtained with composite membranes which were coated over 15 times with a casting solution in which the ratio of B2O3:SiO2 was 0.25:1. Composite membranes with less than 5 coatings showed no ability to separate.