Energy-efficient regeneration of amine-based solvent with environmentally friendly ionic liquid catalysts for CO2 capture

Catalytic CO2 desorption from rich amine solution is a practical approach to reducing energy consumption for amine regeneration. In this study, for the first time, the catalytic effect of environmentally friendly, imidazole series ionic liquids ([Bmim]PF6, [Bmim]BF4, [Bmim]HSO4, [Bmim]NO3, [Bmim]CH3COOH, [Bmim]Cl, [Bmim]Br, and [Bmim]I) is evaluated in terms of CO2 desorption rate, amount of CO2 released, and heat duty. Overall, the [Bmim]PF6 catalyst shows excellent catalytic activity for CO2 desorption, increasing the quantity of CO2 released by 21.35% and reducing the relative heat duty by 17.59%. In addition, the catalytic applicability of [Bmim]PF6 for secondary and tertiary amine systems was evaluated. Of note, the homogeneous [Bmim]PF6 catalyst presents good stability during 5 cycles. The catalyst/MEA (monoethanolamine) solution ratio of 3 wt% retained about 94% of the catalytic performance after five cycling tests without any reactivation step, showing the potential application of this desorption technology for CO2 capture with lower heat duty.