Mechanism and Kinetics of CO2 Absorption into an Aqueous Solution of a Triamino-Functionalized Ionic Liquid

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• 作者：Xiaobin Zhou ; Guohua JingFan Liu ; Bihong Lv ; Zuoming Zhou
• 刊名：Energy & Fuels
• 出版年：2017
• 出版时间：February 16, 2017
• 年：2017
• 卷：31
• 期：2
• 页码：1793-1802
• 全文大小：622K
• ISSN：1520-5029

文摘

A novel ionic liquid (1-aminoethyl-3-methylimidazolium lysinate, [C₂NH₂MIm][Lys]) functionalized with three amino groups had been developed for carbon dioxide (CO₂) capture in this work. The CO₂ absorption loading of [C₂NH₂MIm][Lys] solution was found to be 1.59 mol CO₂/mol IL with a concentration of 0.5 mol/L at 313.15 K, which was much higher than that of the most existing dual functionalized ILs. Besides, [C₂NH₂MIm][Lys] also owned a good regenerability even after 6 regeneration cycles. According to the results of ¹³C nuclear magnetic resonance (¹³C NMR), CO₂ absorption into [C₂NH₂MIm][Lys] solution could be divided into two stages, which began with the formation of carbamate, and followed by the hydration of CO₂ to form carbonate/bicarbonate. Meanwhile, the desorption of the saturated [C₂NH₂MIm][Lys] was proven to be a reverse process of the adsorption. Based on the mechanism results, the kinetics of CO₂ capture into [C₂NH₂MIm][Lys] solution was investigated by using a double stirred-cell absorber at temperatures ranging from 303 to 333 K. Under the pseudo-first-order regime, the overall reaction rate constants (k_ov) and the forward second-order rate constants (k₂) under different concentrations and temperature were obtained, which were both increased considerably as temperature increased. Moreover, the values of enhancement factor (E) were linear with C_RNH2 and temperature. The Arrhenius equation of CO₂ absorption was also estimated, and the activation energy was calculated to be 25.5 kJ·mol^–1.