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.