Combined Process of CO2 Capture by Potassium Carbonate and Production of Basic Zinc(II) Carbonates: CO2 Release from Bicarbonate Solutions at Room Temperature and Pressure

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• 作者：Fabrizio Mani ; Maurizio Peruzzini ; Piero Stoppioni
• 刊名：Energy & Fuels
• 出版年：2008
• 出版时间：May 2008
• 年：2008
• 卷：22
• 期：3
• 页码：1714 - 1719
• 全文大小：316K
• 年卷期：v.22,no.3(May 2008)
• ISSN：1520-5029

文摘

The absorption of CO₂ in aqueous solutions of K₂CO₃ has been investigated at six different temperatures in the range 10–60 °C and at atmospheric pressure. The CO₂ absorption is fast and occurs with high efficiency without any added catalytic activator. The CO₂ capture ranges between 83 and 99% expressed as the percentage of absorbed CO₂ with respect to the neat CO₂ flowing through the absorbent solution. The efficiency of CO₂ removal increases with the temperature, which contrasts with the exoenthalpic nature of the reaction between CO₂ and CO₃²⁻ and the diminished solubility of CO₂ at high temperature. Our finding indicates that the increase of the CO₂/CO₃²⁻ reaction rate with the temperature prevails over the opposite effect on the equilibrium due to the temperature increase. The stripping of pure CO₂ from the HCO₃⁻ solutions has been achieved by adding a zinc(II) salt to the absorbed solutions which releases the captured CO₂ rapidly and completely at room temperature and pressure with the simultaneous separation of solid compounds identified as mixtures of commercially valuable basic zinc carbonates. Although the exact evaluation of the overall merits of the proposed CO₂ capturing technology would require a complete analysis of the energy profile of the process, it is obvious that any improvement of the CO₂ capture process resulting in the associated synthesis of a valuable product without additional energy burdening reduces the cost of CO₂ capture and maximizes the neat balance CO₂(captured) − CO₂(emitted) where CO₂(emitted) represents the total energy bill (electrical, thermal, mechanical) required to sustain the entire cycle of CO₂ abatement.