Cross-Linking Amine-Rich Compounds into High Performing Selective CO(2) Absorbents

Amine-based absorbents play a central role in CO(2) sequestration and utilization. Amines react selectively with CO(2), but a drawback is the unproductive weight of solvent or support in the absorbent. Efforts have focused on metal organic frameworks (MOFs) reaching extremely high CO(2) capacity, but limited selectivity to N(2) and CH(4), and decreased uptake at higher temperatures. A desirable system would have selectivity (cf. amine) and high capacity (cf. MOF), but also increased adsorption at higher temperatures. Here, we demonstrate a proof-of-concept where polyethyleneimine (PEI) is converted to a high capacity and highly selective CO(2) absorbent using buckminsterfullerene (C(60)) as a cross-linker. PEI-C(60) (CO(2) absorption of 0.14 g/g at 0.1 bar/90°C) is compared to one of the best MOFs, Mg-MOF-74 (0.06 g/g at 0.1 bar/90°C), and does not absorb any measurable amount of CH(4) at 50 bar. Thus, PEI-C(60) can perform better than MOFs in the sweetening of natural gas.