A Novel Carbon Dioxide Desorption Phenomena using Potassium Acetate Aqueous Solution

Abstract

A novel CO₂ absorbent, 50–75 wt.% aqueous potassium acetate solution (AcK_(aq)), which showed a CO₂ absorption capacity of ~ 0.2 mol CO₂/mol, and could almost immediately completely desorb CO₂ on addition of 40 wt.% H₂O at 30 ℃ was investigated. This novel phenomenon seemed contrary to the Le Chatelier's principle because H₂O is reactant in this system. After characteristics of products by FTIR and XRD diffraction pattern, the novel desorption behavior was attributed to the acid-base reaction between KH(CH₃COO)₂ and KHCO₃ precipitates within the absorbent sludge. As H₂O was added, both compounds re-dissolved and CO₂ was released. A similar observation was made when the absorbent sludge was heated to temperatures above 60 ℃, owing to an increase in solubility with temperature. The mechanism of CO₂ captured and released by AcK_(aq) was proposed in this study. This novel energy-saving CO₂ absorption and desorption behavior reveals that AcK_(aq) has a high potential for application in the commercial production process.