Cross-Linking Amine-Rich Compounds into High Performing Selective CO₂ Absorbents

摘要

Amine-based absorbents play a central role in CO₂ sequestration and utilization. Amines react selectively with CO₂, 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 CO₂ capacity, but limited selectivity to N₂ and CH₄, 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 CO₂ absorbent using buckminsterfullerene (C₆₀) as a cross-linker. PEI-C₆₀ (CO₂ 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 CH₄ at 50?bar. Thus, PEI-C₆₀ can perform better than MOFs in the sweetening of natural gas.