Breaking the trade-off in amine-based CO2 capture: a tripartite cooperative strategy with ionic liquids, ZIFs and MEA

Despite being a mature technology, the large-scale deployment of amine-based solvents for post-combustion carbon capture is limited by their high energy demand for regeneration, slow absorption-desorption kinetics, and susceptibility to degradation, underscoring the need for more efficient and viable solutions. This study developed an innovative hybrid absorption system that synergistically integrated monoethanolamine (MEA) with imidazolium-based ionic liquids (ILs) and zeolitic imidazolate frameworks (ZIFs) to overcome these limitations. Through systematic optimization of MEA-IL binary blends and the subsequent incorporation of ZIFs, the optimal types and concentrations of ILs and ZIFs were identified, along with key process parameters. The resulting selected formulation, 30 wt% MEA blended with 0.15 g/mL [BMIM][Br] and 0.125 g/mL ZIF-67, delivered substantial performance gains compared to 30 wt% MEA benchmark. The maximum absorption rate and capacity increased by 106.4% and 76.3%, respectively, while the desorption rate and capacity were enhanced by 51.1% and 63.4%. 13 C and 1 H NMR spectroscopy provided clear evidence of the chemical transformations during absorption, enabling the proposal and confirmation of a novel synergistic mechanism in which ILs and ZIFs complementarily enhance the capture process. Moreover, the developed composite system retained over 80% of its initial capacity over six consecutive cycles and showed reliable performance in scale-up experiments up to 40× the baseline, confirming its robustness for industrial implementation. This work elucidates the synergistic mechanisms underlying the MEA-IL-ZIF system and demonstrates its potential as a scalable, energy-efficient, and durable solution for industrial CO 2 capture.