CO2 separation from humidified ternary gas mixtures using a polydecylmethylsiloxane composite membrane

In this work, we investigated the use of a polydecylmethylsiloxane composite membrane as pre-concentrator unit for the separation of CO2 from flue gas streams. The separation properties of the tailor-made membrane were evaluated with both a ternary gas mixture (CO2:N-2:O-2 = 15:80:5) and pure gases (CO2, N-2, O-2) at different temperatures (25, 50 degrees C) and trans-membrane pressure differences (1-6 bar). The membrane exhibited a high permeability close to 1000 barrer, and a moderate CO2/N-2 selectivity of 8.7. The results obtained in mixed gas conditions revealed a certain reduction of CO2 and O(2 )permeability with respect to pure gas, whereas the presence of water vapour did not induce significant changes to mass transport properties.