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Sorption and Separation of CO₂ from Syngas by a Quaternary Ammonium-Based Poly(ionic liquid)

Huang, Mengting, Cao, Jieying, Hong, Yanzhen, Su, Yuzhong, Wang, Hongtao, Li, Jun
Industrial & engineering chemistry process design and development 2019 v.58 no.19 pp. 8317-8322
X-ray diffraction, absorption, carbon dioxide, carbon monoxide, crystal structure, differential scanning calorimetry, freeze drying, ionic liquids, polymerization, synthesis gas
Poly(ionic liquid)s (PILs) have received great attention recently for their potential applications in gas capture. In this work, a quaternization reaction and radical polymerization were applied to the synthesis of a quaternary ammonium-based PIL which was further characterized for its structure and properties. Interestingly, although X-ray diffraction showed an amorphous structure, differential scanning calorimetry evidenced that the PIL prepared by freeze-drying possessed low crystallinity compared to PILs prepared by other drying methods, which contributed to its high CO₂ absorption (236 mg/g) and good CO₂/CO selectivity (6.0) at 303.0 K and 5.0 MPa. To the best of our knowledge, this is the first CO₂/CO selectivity observed for PIL material. An absorption–desorption process by the PIL for CO₂ separation from syngas at 303.0 K and 5.0 MPa was investigated and revealed a complete separation of CO₂ from the syngas. Furthermore, a cyclic absorption experiment confirmed good regeneration of the PIL, suggesting that it could be a potential material to separate and recover CO₂ from syngas.