微通道内醇胺/离子液体复配水溶液吸收CO2的传质特性

研究了微通道内醇胺单乙醇胺(MEA)和甲基二乙醇胺(MDEA)]与离子液体1-丁基-3-甲基咪唑四氟硼酸(Bmim]BF₄])和1-羟乙基-3-甲基咪唑甘氨酸(C₂OHmim]GLY])]复配水溶液吸收CO₂的传质特性。考察了醇胺/离子液体浓度比(c_AA∶c_IL)对液相体积传质系数(k_La)的影响，发现k_La随反应速率的增大而增大。为进一步阐释复配水溶液吸收CO₂的传质机理，分析了比表面积、扩散速率、增强因子和液弹循环对传质速率的影响。结果表明，四种复配溶液中，反应速率和循环频率(f_cir)分别在低流率和高流率下对传质速率起主导作用。k_La可表示为f_cir的函数，低气相流率下k_La与f_cir呈线性关系，斜率与反应速率成正相关，高气相流率下，液弹循环因膜弹传递困难而对整体传质速率的影响减弱，k_La与f_cir呈指数关系，幂律指数小于1。

Mass transfer characteristics of CO2 absorption in alkanolamine/ionic liquid hybrid aqueous solutions in a microchannel

The absorption performance of CO₂ by blends of alkanolamines monoethanolamine (MEA) and methyldiethanolamine (MDEA)] and ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate (Bmim]BF₄]) and 1-hydroxyethyl-3-methylimidazolium glycine (C₂OHmim]GLY])] was investigated in the microchannel. The influence of the concentration ratio of alkanolamine/ionic liquid (c_AA∶c_IL) on the liquid-phase volumetric mass transfer coefficient (k_La) was highlighted. The results show that k_La increases with the increase of reaction rate for all solutions. In order to further elucidate the mass transfer mechanism of CO₂ absorption by the compound aqueous solution, the effects of specific surface area, diffusion rate, enhancement factor and liquid-elastic circulation on the mass transfer rate were analyzed. The results show that the overall mass transfer rate is significantly controlled by chemical reaction rate at low flow rates, and by circulation frequency (f_cir) at high flow rates. Nevertheless, k_La can still be expressed as a mathematical function of f_cir. k_La is linearly related with f_cir at low gas flow rates, and the slope is positively related with the reaction rate. At high gas flow rates, the effect of circulation on mass transfer rate becomes weak due to the difficulty of film-slug exchange. In this case, k_La follows a power-law relation with f_cir whose exponent is less than 1.