Swellable, water- and acid-tolerant polymer sponges for chemoselective carbon dioxide capture

To impact carbon emissions, new materials for carbon capture must be inexpensive, robust, and able to adsorb CO₂ specifically from a mixture of other gases. In particular, materials must be tolerant to the water vapor and to the acidic impurities that are present in gas streams produced by using fossil fuels to generate electricity. We show that a porous organic polymer has excellent CO₂ capacity and high CO₂ selectivity under conditions relevant to precombustion CO₂ capture. Unlike polar adsorbents, such as zeolite 13x and the metal-organic framework, HKUST-1, the CO₂ adsorption capacity for the hydrophobic polymer is hardly affected by the adsorption of water vapor. The polymer is even stable to boiling in concentrated acid for extended periods, a property that is matched by few microporous adsorbents. The polymer adsorbs CO₂ in a different way from rigid materials by physical swelling, much as a sponge adsorbs water. This gives rise to a higher CO₂ capacities and much better CO ₂ selectivity than for other water-tolerant, nonswellable frameworks, such as activated carbon and ZIF-8. The polymer has superior function as a selective gas adsorbent, even though its constituent monomers are very simple organic feedstocks, as would be required for materials preparation on the large industrial scales required for carbon capture.