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

Abstract

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:N2:O2 = 15:80:5) and pure gases (CO2, N2, O2) at different temperatures (25, 50 °C) and trans-membrane pressure differences (1–6 bar). The membrane exhibited a high permeability close to 1000 barrer, and a moderate CO2/N2 selectivity of 8.7. The results obtained in mixed gas conditions revealed a certain reduction of CO2 and O2 permeability with respect to pure gas, whereas the presence of water vapour did not induce significant changes to mass transport properties. Performance maps were thus developed for better understanding whether and in which conditions the membrane developed in this work can be suitable to be used as pre-concentrator.