氨基酸离子液体-MDEA混合水溶液的CO_2吸收性能

摘要

To enhance CO_2 absorption in aqueous solution of N-methyldiethanolamine (MDEA) , four kinds of ionic liquid梩etramethylammonium glycin ( [N_(1111)] [Gly]), tetraethylammonium glycin ( [N_(2222)] [Gly]), tetramethylammonium lysine ( [N_(1111)] [Lys]) and tetraethylammonium lysine ( [N_(2222)] [Lys]) were synthesized and added in MDEA aqueous solution as activator. The performance of CO_2 absorption of the mixed solutions at total mass fraction 30% were tested by the constant volume method, and the proton transfer mechanism in promoting CO_2 absorption was also analyzed. The results indicated that these ionic liquids could greatly enhance the absorption, and the absorption rate increased with increasing concentration of ionic liquid. The mixed absorbents with lysine were of high absorption loads, and the initial absorption rate of [N_(1111)] [Gly]-MDEA aqueous solution was higher than the others used in this work. Moreover, the regeneration efficiency of the mixed solution with added [N_(1111)] [Gly] was 98%, higher than any other absorbents.%为改善N-甲基二乙醇胺(MDEA)水溶液对CO_2气体的吸收性能,选择了四甲基铵甘氨酸([N_(1111)][Gly])、四乙基铵甘氨酸([N_(2222)][Gly])、四甲基铵赖氨酸([N_(1111)][Lys])、四乙基铵赖氨酸([N_(2222)][Lys])4种功能性离子液体作为活化剂与其复配组成新型CO_2吸收剂.用恒定容积法考察了总质量分数为30%的混合溶液吸收CO_2的性能,分析了离子液体在水溶液中与MDEA通过质子传递相互促进吸收CO_2的机理.实验结果显示离子液体能够显著提高MDEA水溶液吸收CO_2的速率,且吸收速率随着添加量的增加而提高.在本文所用的几种混合吸收剂中,阴离子为赖氨酸的离子液体混合吸收剂具有较高的吸收负荷;而[N_(1111)][Gly]-MDEA混合溶液对CO_2的初期吸收速率最快,同时[N_(1111)][Gly]-MDEA混合吸收剂的再生效率高于其他离子液体混合吸收剂,达到98%.