氨基-唑基双功能化离子液体相变吸收剂捕集CO_(2)机制  

Mechanism of CO_(2) capture into amino-azolyl dual-functionalized ionic liquid biphasic solvent

作　　者：吕碧洪[1] 詹晓慧 李昕 周作明[1] 荆国华[1] Bihong Lv;Xiaohui Zhan;Xin Li;Zuoming Zhou;Guohua Jing(College of Chemical Engineering,Huaqiao University,Xiamen 361021,China)

机构地区：[1]华侨大学化工学院,厦门361021

出　　处：《中国科学：化学》2021年第12期1660-1670,共11页SCIENTIA SINICA Chimica

基　　金：华侨大学中青年教师优秀科技创新人才计划(编号:ZQN-YX603);国家自然科学基金(编号:21808074)资助项目。

摘　　要：相变吸收剂是一类极具节能潜力的CO_(2)吸收剂,但现有胺类相变吸收剂存在富相溶液黏度大、再生效率低的缺陷.本文设计合成了一种二乙烯三胺咪唑功能化离子液体,将其溶于乙醇-水混合溶剂中,创新性地构建了氨基-唑基双功能离子液体-乙醇-水相变吸收剂用于CO_(2)捕集.[DETAH][Im]-乙醇-H;O相变吸收剂吸收CO_(2)前为均相溶液,而吸收饱和后发生液液相变,CO_(2)产物主要富集于下层水相,当乙醇在混合溶剂中的比例为70 v/v%时,富相溶液吸收容量占总CO_(2)容量(1.548 mol CO_(2)/mol absorbent) 92%而体积仅占32%;且在乙醇作为再生活化剂时,富相溶液经过4次再生仍保持其初始负载的90%以上.[DETAH][Im]中的氨基和唑基官能团与CO_(2)均可发生化学反应,保证了体系高效的CO_(2)容量.且[Im]-H和乙醇均可增强CO_(2)反应产物氨基甲酸酯分解转化,形成易分解的HCO_(2)/CO_(2)和碳酸乙酯,确保富相溶液的高再生效率.由于密度大的产物在水中的氢键作用和极性均强于乙醇,促使产物向下层水溶液中富集,而密度小的乙醇处于上层,最终形成液-液相变.Biphasic solvents exhibit great potential for saving energy in CO_(2)capture.However,the efficiency of the available amine-based biphasic solvent is compromised due to the high viscosity and low regeneration efficiency of the rich phase solution.In this work,a novel amino-azolyl dual-functional ionic liquid/ethanol/water ([DETAH][Im]/EtOH/H;O) biphasic solvent for CO_(2)capture was proposed via dissolution of a diethylenetriamine-imidazole functionalized ionic liquid ([DETAH][Im]) in the mixed ethanol-water solvent.This biphasic solvent transitioned from homogeneous phase to liquid-liquid phase after saturation of CO_(2)capture.And the formed products during CO_(2)capture were mainly concentrated in the lower phase.When the concentration of ethanol was 70 v/v%,the CO_(2)loading of the rich solution(1.548 mol CO_(2)/mol absorbent) accounted for 92 of the total CO_(2)loading whereas the volume only accounted for 32%.And ethanol was used as a regeneration activator,which could guarantee that the rich liquid retained more than 90% of its initial load after four times of regeneration.The reaction of both the amino and azole group functional groups in[DETAH][Im]with CO_(2)ensured the efficient CO_(2)loading of the biphasic solvent.In addition,[Im]-H and ethanol can enhance the hydrolysis of carbamate to form easily decomposed HCO_(2)/CO_(2)and ethyl carbonate and the high regeneration efficiency of the rich liquid can be obtained.The hydrogen bond and polarity products with high density in water were stronger than ethanol,leading to the enrichment of the products in the lower aqueous solution.Nevertheless,ethanol with low density is in the upper layer,eventually forming liquid-liquid phase transition.

关 键 词：二氧化碳 功能化离子液体 相变吸收剂 机理 

分 类 号：TQ028.17[化学工程] X701[环境科学与工程—环境工程]