Abstract:

The CO₂ absorption and desorption performances of nine alcohol amines were compared. Among them, there were two kinds of solutions that showed the better stability of absorption-desorption performance, which contained N-ethylethanolamine (EMEA)+diethylaminoethanol (DEEA)+piperazine (PZ) and 2-amino-2-methyl-1,3-propanediol (AMPD)+piperazine (PZ)+H₂O. The average desorption rate of the solvents were above 94.0% after two cyclic tests. The solutions were subjected to thermal degradation for 144h and oxidative degradation for 96h. It was found that the absorption-desorption performance of EMEA+DEEA+PZ solution after thermal degradation was stable. The average absorption amount and desorption amount of the solution increased slightly by 1.58L CO₂/kg solution and 0.35L CO₂/kg solution, respectively, and the average desorption rate decreased by 2.0%. While oxidative degradation caused the average absorption amount and desorption amount of the solution to decrease by 0.45L CO₂/kg solution and 1.75L CO₂/kg solution, respectively, and the average desorption rate decreased by 2.3%. The thermal degradation had a distinct impact on the absorption-desorption performance of AMPD+PZ+H₂O solution, which caused a decrease in the average absorption amount and desorption amount of the solution by 5.63L CO₂/kg solution and 4.03L CO₂/kg solution, respectively, and the average desorption rate increased by 2.3%. After oxidative degradation, the average absorption amount and desorption amount of the solution decreased by 1.05L CO₂/kg solution and 0.70L CO₂/kg solution, respectively, and the average desorption rate increased by 0.6%.The liquid mass spectrometry analysis showed that the concentrations of EMEA and AMPD decreased by 19.7% and 71.8% due to thermal degradation, 18.2% and 74.5% due to oxidative degradation, respectively. The thermal and oxidative degradation experiments demonstrated that EMEA+DEEA+PZ had the better anti-degradation performance than AMPD+PZ+H₂O. The mechanisms of thermal and oxidative degradation of the two kinds of alcohol amines were speculated based on the results of electrospray mass spectrometry, in which oxazolidinones were generated in thermal degradation and acids were generated in oxidative degradation. In both cases, oxidative degradation had negative effects on both solutions, while thermal degradation did not.

Key words: alcohol amines, CO₂ capture, absorption, desorption, degradation

摘要：

比较了9种不同配方醇胺溶液对CO₂的吸收解吸性能。其中，N-乙基乙醇胺（EMEA）+二乙氨基乙醇（DEEA）+哌嗪（PZ）和2-氨基-2-甲基-1,3丙二醇（AMPD）+哌嗪（PZ）+水（H₂O）两种溶液的吸收解吸的稳定性最佳，平均解吸率高于94.00%。本文对这两种溶液进行了144h热降解和96h氧化降解实验，结果表明热降解后的EMEA+DEEA+PZ溶液的吸收解吸性能稳定性较高，每千克溶液对CO₂的平均吸收量、平均解吸量略有升高，分别升高1.58L、0.35L，平均解吸率下降2.04%；而氧化降解造成每千克EMEA+DEEA+PZ溶液对CO₂的平均吸收量、平均解吸量分别下降0.45L、1.75L，平均解吸率下降2.25%；热降解对于AMPD+PZ+H₂O溶液吸收解吸性能影响较大，造成每千克该溶液对CO₂的平均吸收量、平均解吸量分别下降5.63L、4.03L，平均解吸率升高2.32%；在经过氧化降解之后，每千克AMPD+PZ+H₂O溶液对CO₂的平均吸收量、平均解吸量分别下降1.05L、0.70L，平均解吸率升高0.59%。液质联用分析结果表明，热降解导致EMEA浓度减小了19.67%，AMPD浓度减小了71.89%；氧化降解导致EMEA浓度减小了18.18%，AMPD浓度减小了74.53%。由此说明，EMEA+DEEA+PZ比AMPD+PZ+H₂O具有更佳的抗降解性能。同时，根据电喷雾质谱结果对两种溶液的热降解、氧化降解的机理进行推测，热降解中生成恶唑烷酮类物质，氧化降解则是生成酸类物质。其中，氧化降解对两种溶液都造成了负面影响，而热降解则不然。

关键词: 醇胺, 二氧化碳捕集, 吸收, 解吸, 降解