Separation of CO2 from humidified ternary gas mixtures using thermally rearranged polymeric membranes

Abstract

The recently developed thermally rearranged (TR) polymeric membranes displayed superior gas separation properties over conventional polymeric membranes, owing to the presence of micro-pores appropriately tuned in cavities size and distribution, thus offering great advantages in gas separation applications, especially in CO2 capture from post-combustion flue gas streams. In this work, the transport properties (flux, permeance and selectivity) of TR polymeric hollow fiber membranes were evaluated with both single gases (CO2, N-2, O-2) and ternary gas mixture (CO2:N-2: O-2=15:80:5) at different temperatures (25, 50, 75 degrees C) and trans-membrane pressure differences (2-5 bar). The results revealed that the CO2 permeance measured under the mixed-gas condition remained the same as the single gas CO2 permeance, while the permeances of other gases decreased, thus leading to a favored increase in selectivity. The effect of water vapor in a ternary gas mixture was studied for the first time, considering that most of the streams of interest contain large amount of water. The presence of water vapor induced a significant permeance decrease for all the three components and a negligible reduction in selectivity. Globally the membranes showed good performance in the whole range of operating conditions investigated.