Influence of substitution of water by organic solvents in amine solutions on absorption of CO2
Influence of substitution of water by organic solvents in amine solutions on absorption of CO2
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DOI：
10.1016/j.ijggc.2018.07.029
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发表时间：
2018-11-01
影响因子：
3.9
通讯作者：
Gu, Sai
中科院分区：
文献类型：
--
作者：
Garcia, Monica;Knuutila, Hanna K.;Gu, Sai
胺类水溶液是化学吸收二氧化碳最常用的溶剂。在胺水溶液中用有机溶剂代替部分水，目的是利用较低的分压和较高的CO2溶解度。本文研究了四种有机溶剂对溶液密度、粘度、N2O溶解度和吸附动力学的影响。将有机溶剂一甘醇(MEG)、二甘醇(DEG)、三甘醇(TEG)和卡比特醇(CARBITOL)分别与MEA和DEEA-MAPA共混胺溶液混合。结果表明，有机溶剂的加入提高了聚合物的密度和粘度。此外，当部分水被有机溶剂取代时，用于估计二氧化碳在反应体系中的物理溶解度的N2O溶解度会增加。在双搅拌槽中进行的动力学实验表明，在所研究的整个温度范围内，在5 M MEA水溶液中，部分水的取代都增加了CO2的传质系数和动力学系数，而在3M DEEA+2M MAPA溶液中的取代并不是很有利，只有MEG的取代对传质系数和动力学系数都有增强作用。由于MEA有机溶剂共混物的粘度比DEEA+MAPA共混物的粘度低，对动力学的负面影响较小，这部分可以用不同体系中粘度和N2O溶解度的变化来解释。同时，与DEEA+MAPA共混物相比，MEA共混物中N2O溶解度的增加要大得多，从而导致更多的CO2可用于反应。最后，结合稀释介质的介电常数对动力学系数的结果进行了讨论。
Aqueous amine solutions are the most used solvents for chemical absorption of CO2. Substituting part of the water by organic solvents in aqueous amine solutions aims to take advantage of the lower partial pressure and higher CO2 solubility. In this work, the influence of four organic solvents on solution density, viscosity, N2O solubility and absorption kinetics are studied. The organic solvents, Monoethylene Glycol (MEG), Diethylene Glycol (DEG), Triethylene Glycol (TEG) and CARBITOL, are blended with two amine solutions: MEA and DEEA-MAPA blend. The results show that the addition of organic solvents increases the density and viscosity. Furthermore, the N2O solubility, used to estimate the physical solubility of CO2 into a reactive system, increases when part of the water is substituted with an organic solvent. The kinetic experiments with a double stirred cell showed that in case of aqueous 5 M MEA, the substitution of part of the water increases both the mass transfer and kinetic coefficients of the CO2, whereas the substitution in the 3M DEEA + 2M MAPA solution was not that favorable and only the substitution of MEG showed enhancement on the mass transfer and kinetic coefficients over the whole temperature range studied. The results can be partly explained by the changes in viscosity and N2O solubility in the different systems, since the viscosity of the MEA organic solvent blends is lower compared to that of DEEA + MAPA blends and have less negative influence on the kinetics. At the same time, the increase of N2O solubility in the MEA blends is much higher than in DEEA + MAPA blends, resulting in more CO2 available to react. Finally, the kinetic coefficients results are discussed together with dielectric constant of the dilution media.