Effect of humidity and flue gas impurities on CO2 permeation of a polymer of intrinsic microporosity for post-combustion capture

The impact of humidity and flue gas impurities on PIM-1 membrane performance for post combustion capture, i.e. CO2 permeability and CO2/N2 selectivity, is investigated in this study. The presence of humidity in the feed stream induces a decrease in the permeability coefficients of both CO2 and N2, from 7010 Barrer (dry state) to 4135 Barrer (%RH = 50%) and 360 Barrer (dry state) to 250 Barrer (%RH = 50%) respectively. PIM-1 shows also a high water permeability (58800 Barrer) which increases with the relative humidity of the feed. The interaction with flue gas contaminants (NOx, SOx, Water) leads to a dramatic decrease of the membrane performance even after short exposure and FTIR analysis confirmed modifications of the chemical structure of PIM-1 caused by the acid environment. These results indicate that test with flue gases have to be considered for all novel materials proposed for carbon capture applications since the decrease in membrane permeability in presence of water and other impurities has to be taken into account during the design of the separation process.