Gas permeation properties of amine loaded mesoporous silica membranes for CO_2 separation

摘要

Gas permeation properties of amine loaded mesoporous silica membranes for CO_2 separation were evaluated using a mixture of CO_2/N_2 under dry and wet conditions. Although the 3-aminopropyl loaded mesoporous silica membrane was highly CO_2 selective under dry conditions, its selectivity declined in the presence of water. By contrast, 3-trimethoxysilylpropyl-diethylenetriamine (TA) loaded mesoporous silica membranes showed high CO_2 selectivity even under wet conditions. Water condensed within the mesopores inhibited CO_2 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 CO_2 molecules still preferentially permeated in the presence of water. The size of mesopores and modifying reagents significantly influences CO_2 selectivity. In addition, the affinity between organo-amines and polar molecules may also be exploited to increase selectivity.