Low-cost supported ionic liquid [TETA][HCOO]/X-5: Adsorption and regeneration performance for CO2 capture from flue gas

In this study, cost-effective protic amine-based ionic liquids (PABILs) were synthesized via acid-base neutralization and impregnated onto porous silica (SiO₂) and X-5 resin to prepare a series of supported ionic liquid (SIL) sorbents. Their CO₂ adsorption performance and regeneration characteristics in simulated flue gas were systematically investigated. The [TETA][HCOO]/X-5 sorbent showed the highest CO₂ adsorption capacity at an optimal loading of 63 %, reaching 2.02 mmol/g at 30 °C and 1 bar. This performance surpasses most supported ionic liquid systems reported previously. The sorbent is also economically promising, as [TETA][HCOO] can be synthesized from low-cost, readily available precursors at an estimated cost of $4.96/kg. A moderate humidity level (65 % RH) enhanced the sorbent’s performance, whereas excessive humidity led to competition for adsorption sites, thereby reducing CO₂ uptake. In terms of regeneration performance, N₂ purging exhibited effective regeneration at temperatures ranging from 100 °C to 120 °C, whereas air purging led to incomplete desorption. Vacuum thermal regeneration (VTR) outperformed N₂ purging at relatively lower temperatures and proved to be a more favorable option in scenarios where the separation of high-purity CO₂ gas is required.