Gas separation by differential permeation

摘要

Diffusion barriers for gas separation comprise films of liquids or quasi-liquids on supports. Specified liquids include water and diethylene glycol: the water may be immobilized to form a quasi liquid by the addition of e.g. agar, or by incorporation as a plasticizer in a film of polyvinyl alcohol, the polymer being cross-linked to prevent absorption of the water thereon. The support may be a solid porous material suitably treated if necessary so as not to be wetted by the liquid, or a film of a solid permeable material, such as a silicone rubber. In Fig. 2 (not shown) a layer of liquid 21 is supported on an unwetted porous plate 22 which may be of PTFE, or a finely woven paper, cloth, screen or porous plate treated with an anti-wetting agent such as PTFE. In Fig. 3 (not shown) is a film 31 of water of diethylene glycol supported on a permeable layer 32 of silicone rubber on a screen 33. The depth of the liquid is preferably ten times that of the support so that the permeation rates are effectively controlled by the liquid. The thickness of the support may for example be, 10-4 in. In Fig. 4 (not shown) is shown a quasi-liquid film of e.g. water immobilized by the addition of 1% of agar or polyvinylalcohol "plasticized" with water by e.g. exposure to water vapour. The sintered metal plate 42 supports the film 41. Other supports such as untreated paper may also be used. The apparatus may be used to separate O2 from CO2