A study was made on the permeation rate of pure gases including helium
, hydrogen, oxygen, nitrogen, carbon dioxide and methane, and the sepa
ration of CO2/CH4 gas mixtures by a silicone-coated aromatic polyamide
membrane. The ideal and actual separation factors of the polymer towa
rds these gases were calculated. The membranes were prepared by the ph
ase-inversion technique and coated with silicone rubber after drying.
While the permeation rates of He, H-2 and CO2 were not affected signif
icantly by coating, the permeation rates of N-2 and CH4 gases decrease
d to below the detectable limit of the flow meter. The permeation rate
of O-2 decreased after coating. The actual separation factor for mixt
ures of CO2/CH4 varied from 64 to 166, one of the highest separation f
actors reported in the literature.