College of Environment , Zhejiang University of Technology , Hangzhou 310014 , China.
Zhejiang University of Water Resource and Electric Power , Hangzhou 310018 , China.
Environ Sci Technol. 2019 Apr 16;53(8):4470-4479. doi: 10.1021/acs.est.9b00040. Epub 2019 Mar 29.
The biphasic solvent-based absorption process has been regarded as a promising alternative to the monoethanolamine (MEA)-based process because of its high absorption capacity, phase separation behavior, and potential for conserving energy for CO capture. A trade-off between the absorption capacity and phase separation ratio is critical for developing an advanced biphasic solvent. Typically, water content in the biphasic solvent can be manipulated to tune the phase separation behavior. To explore the relationship between water content and phase separation behavior, an inert organic solvent, 1-methyl-2-pyrrolidinone, was added as a substitute for water in a biphasic solvent, specifically a triethylenetetramine (TETA) and 2-(diethylamino)ethanol (DEEA) blend. Moreover, the water content-kinetics and thermodynamics relationships were also evaluated. Experimental results revealed that reducing the water content was beneficial for phase separation but adverse for adsorption capacity. Kinetic analysis indicated that the water content did not significantly affect the rate of CO absorption at a rich loading. Furthermore, the regeneration heat decreased with the water content. The regeneration heat of TETA-DEEA with a water content of 20 wt % was almost 50% less than that of MEA solution. C nuclear magnetic resonance analysis revealed that the water content did not affect the reaction mechanism between CO and amines.
双相溶剂吸收法由于其高吸收能力、相分离行为以及在 CO 捕集中节约能源的潜力，被认为是一种很有前途的单乙醇胺（MEA）工艺替代方法。在开发先进的双相溶剂时，吸收能力和相分离率之间的权衡是至关重要的。通常，可以通过控制双相溶剂中的含水量来调节相分离行为。为了探索含水量与相分离行为之间的关系，在双相溶剂中添加了一种惰性有机溶剂 1-甲基-2-吡咯烷酮，以替代水，具体为三乙烯四胺（TETA）和 2-（二乙基氨基）乙醇（DEEA）的混合物。此外，还评估了水含量-动力学和热力学关系。实验结果表明，降低水含量有利于相分离，但不利于吸附能力。动力学分析表明，在富载条件下，水含量对 CO 吸收速率的影响不大。此外，再生热随水含量的降低而降低。水含量为 20wt%的 TETA-DEEA 的再生热几乎比 MEA 溶液低 50%。碳核磁共振分析表明，水含量并不影响 CO 与胺之间的反应机制。
