CO₂ capture with complex absorbent of ionic liquid and water

A sort of functional hydrophilic ionic liquid (ILs), [NH₂-C₃mim] [Br], was prepared by the green synthesis route. Aiming at reduction of operational costs for CO₂ absorption and regeneration and reuse of absorbent, experiments on CO₂ capture and absorbent-desorption for regeneration and reuse were carried out. Experimental results showed that specific capacity of CO₂ (on the basis of complex absorbent or ILs component) changed with the concentration of ILs in the complex absorbent. In the initial stage, CO₂ absorption rates changed obviously with the concentration of ILs, and an appropriate ratio of complex absorbent was obtained (mass ratio of ILs to water was 1.38:1). Moreover, continuous CO₂ capture and absorbent regeneration experiments were carried out with a pilot scale equipment for absorption enhanced by super gravity field and desorption via counter-current contact under vacuum or by heating with water-based ionic liquid solution, improved hot potassium carbonate and activated complex alcamines as absorbent respectively. The results indicated good absorption for CO₂ capture with water-based ionic liquid solution, improved hot potassium carbonate and activated complex alcamines under super gravity field, and the absorption rates for CO₂ were 98%, 96% and 90% respectively. Adsorbent could be regenerated and reused after CO₂ removal under vacuum or by heating. Water-based ionic liquid solution desorption under vacuum and at normal temperature was more practicable.