Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
IHI Corporation, Toyosu 3-chome, Koto-ku, Tokyo 135-8710, Japan.
Environ Sci Technol. 2020 Jul 21;54(14):8999-9007. doi: 10.1021/acs.est.0c02595. Epub 2020 Jun 30.
Electrochemically mediated amine regeneration (EMAR) was recently developed to avoid the use of thermal means to release CO captured from postcombustion flue gas in the benchmark amine process. To address concerns related to the high vapor pressure of ethylenediamine (EDA) as the primary amine used in EMAR, a mixture of EDA and aminoethylethanolamine (AEEA) was investigated. The properties of the mixed amine systems, including the absorption rates, electrolyte pH and conductivity, and CO capacity, were evaluated in comparison with those of solely EDA. The mixed amine system had similar properties to that of EDA, indicating no significant changes would be necessary for the future implementation of the EMAR process with mixed amines as opposed to that with just EDA. The electrochemical performance of the mixed amines in terms of the cell voltage, gas desorption rate, electron utilization, and energetics was also investigated. A 50/50 mixture of EDA and AEEA displayed the lowest energetics: ∼10% lower than that of 100% EDA. With this mixture, a continuous EMAR process, in which the absorption column was connected to the electrochemical cell as the desorption stage, was tested over 100 h. The cell voltage was very stable and there was a steady gas output close to theoretical values. The desorbed gas was further analyzed and found to be 100% CO, confirming no evaporation of the amine. The mixed absorbent composition was also characterized using titration and nuclear magnetic resonance (NMR) spectroscopy, and the results showed no amine degradation. These findings that demonstrate a stable, low vapor pressure absorbent with improved energetics are promising and could be a guideline for the future development of EMAR for CO capture from flue gas and other sources.
电化学介导的胺再生（EMAR）最近被开发出来，以避免使用热手段来释放基准胺工艺中从烟道气中捕获的 CO。为了解决与作为 EMAR 中主要胺使用的乙二胺（EDA）高蒸气压相关的问题，研究了 EDA 和氨乙基乙醇胺（AEEA）的混合物。与仅 EDA 相比，评估了混合胺体系的吸收速率、电解质 pH 值和电导率以及 CO 容量等性质。混合胺体系具有与 EDA 相似的性质，表明在未来实施 EMAR 工艺时，混合胺与仅 EDA 相比，不需要进行重大改变。还研究了混合胺在电池电压、气体解吸速率、电子利用率和能量学方面的电化学性能。EDA 和 AEEA 的 50/50 混合物显示出最低的能量学：比 100%EDA 低约 10%。使用该混合物，连续进行了超过 100 小时的 EMAR 过程测试，其中吸收柱连接到电化学电池作为解吸阶段。电池电压非常稳定，气体输出稳定接近理论值。进一步分析解吸气体，发现其为 100%CO，证实胺没有蒸发。还使用滴定和核磁共振（NMR）光谱对混合吸收剂成分进行了表征，结果表明胺没有降解。这些研究结果表明，具有稳定、低蒸气压和改进能量学的吸收剂具有广阔的应用前景，可为从烟道气和其他来源中捕获 CO 的 EMAR 的未来发展提供指导。
