Separation of Gas Mixtures Containing Carbon Dioxide Using Membranes Based on Polytricyclononenes with Trialkoxysilyl Groups

Separation of CO₂/CH₄ and CO₂/N₂ mixtures containing from 20 to 50% CO₂ on membranes based on polytricyclononenes with tri(n-alkoxy)silyl groups containing substituents with alkyl fragments of different lengths (one to four carbon atoms), prepared by vinyl-addition polymerization, was studied. The separation selectivity for these mixtures is close to the corresponding ideal selectivity. The gas transport characteristics slightly depend on the pressure of the gas feed flow. The best results are obtained for the polymer with methyl groups in pendant substituents. The parameters of this polymer are located above the 2015 upper bound in the Robeson diagram for CO₂/CH₄ gas mixtures.