Polyethylenimine "Snow": An Emerging Material for Efficient Carbon Removal

Amine-functionalized solid adsorbents are one of the most promising alternatives to the conventional "amine scrubbing" for carbon capture with a number of prominent examples being reported. However, their widespread application in industry is unfulfilled due to their overall performance and complex fabrication, which relies on a porous support. In this "proof of concept" study, we report an approach for generating a new type of material called polyethylenimine (PEI) 'snow', which can be prepared for use in under 15 min. The material does not require a support, and the resulting CO₂ uptake is the highest reported to date for PEI-functionalized materials. This was achieved through a rigorous material program that identified conditions where a material with the requisite properties could be generated. From experimental measurements, the virtual dryness of the PEI snow results in fast CO₂ absorption kinetics, which is comparable to conventional solid adsorbents, but its CO₂ uptake (451.5 mg CO₂/g PEI) is the highest reported so far. Breakthrough curves demonstrate the outstanding CO₂ selectivity over N₂ and CH₄ (above 1000), with the potential for post-combustion capture and natural gas sweeting. This strategy can be applied in affordable and efficient gas treatment for various large point sources.