纯氨基酸构建的固-液相变吸收剂存在二氧化碳(CO2)吸收速率低、难再生等缺陷。据此，以 CO2 吸收与沉淀能力较好的丙氨酸钾(K-Ala)为主吸收剂，以耐降解、反应性高的哌嗪(PZ)为活化剂，以可促进固相生成的正丙醇(NPA)为溶剂，构建了K-Ala+PZ+NPA+H2O新型固-液相变CO2 吸收体系，并对该体系的CO2 捕集性能、反应机理、相变机制等进行了研究。实验结果表明饱和CO2 负荷为 0。68 mol·mol-1，体系再生效率达 83。04%，捕集性能良好。饱和固相中主要包含丙氨酸钾氨基甲酸酯(K-Ala-COO-)、哌嗪氨基甲酸酯(PZ-COO-)和碳酸氢盐(HCO3-)。上述产物比原组分极性更高、溶剂化自由能更低，因此形成了产物间自聚并出现固液分相行为。
CO2 capture by amino acid-based solid-liquid phase change absorbents and reaction-phase change mechanisms
Solid-liquid phase change absorbents based on pure amino acids have defects such as low carbon dioxide(CO2)absorption rate and poor regeneration.Therefore,potassium alanine(K-Ala)which has good comprehensive performance of CO2 absorption loading and precipitation capacity was used as the main component.Piperazine(PZ)which is resistant to degradation and has high reactivity was used as the activator,while n-propanol(NPA)which promotes the formation of solid phase products was used as the solvent.A novel solid-liquid phase change CO2 absorption system K-Ala+PZ+NPA+H2O was constructed,and CO2 capture performance,reaction mechanism and phase change mechanism of the absorption system were studied.The saturated CO2 absorption loading of this system is 0.68 mol·mol-1,and the regeneration efficiency is 83.04%.The saturated solid phase mainly contains K-Ala carbamate(K-Ala-COO-),PZ carbamate(PZ-COO-)and bicarbonate(HCO3-).Due to the higher polarity and lower solvation free energy of the above products compared with the original components,self-polymerization between the products occurred and finally the phase separation behavior formed.
carbon dioxide capturesolid-liquid phase change absorbentamino acidsquantum chemical computation
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