The effect of condensable minor components on the gas separation performance of polymeric membranes for carbon dioxide capture

Polymeric membranes as a carbon dioxide capture technology have a number of advantages over other approaches, including their low cost, high performance separation, ease of synthesis, as well as mechanical and thermal stability. However, condensable components in flue gas, in particular water, undergo competitively adsorption with carbon dioxide within the membranes, resulting in a reduction in CO2 permeability. Furthermore, on a longer timescale plasticization of the membrane can occur, turning the glassy polymer to a more rubbery state, which alters both gas permeability and selectivity. Here, the impact of water on three glassy polymeric membranes are studied; polysulfone, Matrimid and 6FDA-TMPDA (a polyimide). The purpose of this work is to model the behavior of gas separation membranes under humid conditions that mimic real flue gas. This will assist in analyzing the performance of glassy gas separation membranes in planned CO2 capture trials on both pre- and post-combustion carbon capture.Upon exposure to water in the feed, all three membranes, Matrimid, polysulfone and 6FDA-TMPDA experience reduced CO2 permeability indicative of competitive adsorption. Over a longer timescale, both polysulfone and 6FDA-TMPDA recover some of the loss in permeability performance, due to plasticization by water. Matrimid displays no plasticization behavior.