Kinetics and new mechanism study of CO 2 absorption i nto water and tertiary amine solutions b y stopped‐Flow technique

作者：Sen Liu, Hongxia Gao, Xiao Luo, Zhiwu Liang · 发表于：AIChE Journal · 年份：2018 · DOI：10.1002/aic.16469 · 被引用次数：33 · 研究领域：Carbon Dioxide Capture Technologies、Membrane Separation and Gas Transport、CO2 Reduction Techniques and Catalysts

The objective of the present work was to find the accurate kinetic models and mechanism for CO 2 absorption into tertiary amine solution, aiming at understanding the contribution of the CO 2 reaction with H 2 O, OH − , and tertiary amines on the overall reaction rate. First, the kinetics of CO 2 absorption into water instead of a buffer solution were studied using the stopped‐flow technique at 293–313 K, with initial CO 2 molar concentration of 1.1–37.3 mM. The experimental first‐order reaction rate constant ( ) was determined to be about 1000 times larger than the value for CO 2 absorption into buffer solution reported in the reference. The was then correlated by a proposed semiempirical model and a simplified theoretical model, giving the activation energy for CO 2 reacting with H 2 O as fitted by the simplified theoretical model in good agreement with the value of previous research. Also, the pH values and hydroxyl ion concentrations of aqueous Diethylaminoethanol (DEEA) solutions were determined at 293–313 K, with DEEA molar concentration of 0.1–0.4 M and CO 2 loading of 0–0.626 mol/mol. In addition, the observed first‐order reaction rate constant ( k 0_DEEA ) of binary DEEA‐H 2 O solution with DEEA molar concentration of 0.1–0.4 M reacting with CO 2 was determined at 293–313 K. It should be pointed out that the kinetic experiments of CO 2 absorption into DEEA solution was done with the molar ratio of DEEA to CO 2 fixed at 20. The values of k 0_DEEA were then fitted and p...