Gas permeation properties of amine loaded mesoporous silica membranes for CO2 separation

Gas permeation properties of amine loaded mesoporous silica membranes for CO2 separation were evaluated using a mixture of CO2/N-2 under dry and wet conditions. Although the 3-aminopropyl loaded mesoporous silica membrane was highly CO2 selective under dry conditions, its selectivity declined in the presence of water. By contrast, 3-trimethoxysilylpropyl-diethylenetriamine (TA) loaded mesoporous silica membranes showed high CO2 selectivity even under wet conditions. Water condensed within the mesopores inhibited CO2 permeation of the 3-aminopropyl loaded membrane. However, the subnanometer effective pore size of the TA loaded membrane (because of the long molecular length of TA), meant that CO2 molecules still preferentially permeated in the presence of water. The size of mesopores and modifying reagents significantly influences CO2 selectivity. In addition, the affinity between organo-amines and polar molecules may also be exploited to increase selectivity.