有机胺电化学再生系统性能与影响因素

Performance and influencing factors of organic amine electrochemical regeneration system

  • 摘要: 在碳中和背景下,碳捕集、利用与封存(CCUS)是实现节能减排的关键技术。针对有机胺溶液在碳捕集过程中存在的高能耗和降解问题,电化学介导胺再生(EMAR)是一种极具应用前景的碳捕集技术,原理是利用Cu(II)和吸收剂之间的络合实现二氧化碳(CO2)的释放。使用吸收解吸实验装置,测量了9种吸收剂的CO2吸收解吸性能。发现伯、仲胺溶液相对叔胺拥有更好的吸收性能,但在传统热解吸方法下再生效率不高,具有很大的改进潜力。直接向负载CO2饱和的胺溶液中加入Cu(II),发现溶液展现出优秀的解吸性能。在相同条件下测试了不同有机胺溶液的阴、阳极电化学参数,综合考虑极化电位、电流密度和溶液内阻等电化学参数,以及吸收解吸性能和原料成本等,选择了二乙烯三胺(DETA)作为研究对象继续后续实验条件的探索。利用电化学反应装置对吸收CO2饱和的30%(质量分数)DETA水溶液进行研究,探究4种影响因素:电解质种类、电解质质量摩尔浓度、Cu(II)质量摩尔浓度和温度对电化学反应过程的影响。研究发现NaBr在所选4种电解质中具有更低的腐蚀电位,且在高质量摩尔浓度下电位的优势更为明显,更有利于反应的进行。高电解质质量摩尔浓度能使腐蚀电位相对未加入电解质时下降达到0.2 V,且它和温度都能有效降低电荷转移电阻,提高反应速率。此外,低Cu(II)负荷利于Cu(II)的生成和CO2的解吸,溶液Cu(II)质量摩尔浓度的增加会抑制阳极铜氧化为铜离子的过程,有利于单质铜的生成和DETA的再生。

     

    Abstract: In the context of carbon neutrality, the carbon capture, utilization and storage (CCUS) is a key technology to achieve energy conservation and emission reduction. In view of the high energy consumption and degradation of organic amine solutions in the carbon capture process, an electrochemically mediated amine regeneration (EMAR) is a promising carbon capture technology, which uses the complexation between Cu(II) and absorbent to achieve the release of CO2. The CO2 absorption and desorption performance of nine absorbents was measured using the absorption and desorption experimental device. It was found that the primary and secondary amine solutions have better absorption performance than tertiary amines, but the regeneration efficiency is not high under the traditional thermal desorption method, and there is great potential for improvement. The Cu(II) was added directly to the CO2-saturated amine solution, and the solution was found to exhibit excellent desorption properties. Under the same conditions, the cathodic and anode electrochemical parameters of different alcohol amine solutions were tested, and the electrochemical parameters such as polarization potential, current density and solution internal resistance, as well as absorption and desorption performance and raw material cost were comprehensively considered, and the DETA was selected as the research object to continue the exploration of subsequent experimental conditions. The electrochemical reaction device was used to study the 30% DETA aqueous solution saturated with CO2, and the influence of four influencing factors, i.e. electrolyte type, electrolyte concentration, Cu(II) concentration and temperature on the electrochemical reaction process, was explored. It was found that NaBr has a lower corrosion potential among the four selected electrolytes, and the advantage of potential at high concentrations is more obvious, which is more conducive to the reaction. The high electrolyte concentration can reduce the corrosion potential to 0.2 V relative to the absence of electrolyte, and both it and temperature can effectively reduce the charge transfer resistance and increase the reaction rate. In addition, the low Cu(II) load is conducive to the formation of Cu(II) and the desorption of CO2, and the increase of the concentration of Cu(II) in solution will inhibit the oxidation of anode copper to copper ions, which is conducive to the formation of elemental copper and the regeneration of DETA. The study results provide reference data for the engineering application of this technology.

     

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