胺溶液吸收CO_2的量子化学分析  

Quantum Chemical Analysis of CO_2 Solvent in Aqueous Amine Solutions

作　　者：武洁[1] 周月桂[1] 金旭东[1] 徐德厚[1] 

机构地区：[1]上海交通大学机械与动力工程学院热能工程研究所,上海200240

出　　处：《工程热物理学报》2015年第3期668-672,共5页Journal of Engineering Thermophysics

基　　金：国家自然科学基金资助项目(No.51276110);教育部新世纪优秀人才支持计划项目(No.NCET-10-0584);上海交通大学晨星青年学者奖励计划B类计划(No.12X100010102)

摘　　要：胺溶液吸收燃煤电厂烟气中CO_2是目前减少CO_2排放的有效技术途径。采用真实溶剂似导体屏蔽模型COSMO-RS结合密度泛函理论DFT预测了多种伯胺和仲胺溶液的pK_a值,计算中采用了不同的密度泛函和基组方法,表明在BLYP/TZP方法下得到的pK_a值与已有实验值符合最好。在BLYP/TZP方法下计算了各组分的吉布斯自由能,评估了胺溶液吸收CO_2后溶液中氨基甲酸离子与碳酸氢根离子的比率。此外,通过液相状态下的DFT计算研究了氨甲基丙醇(AMP)溶液吸收CO_2过程中碳酸氢根离子生成的反应机理,结果表明碳酸氢根离子更有可能是由胺、H_2O和CO_2直接反应生成,而不是由氨基甲酸离子水解生成。Chemical absorption using aqueous amine solutions is an important method to capture CO_2from the flue gas of coal-fired power plants.A conductor-like screening model for real solvents(COSMO-RS) was performed to predict the base strength of different primary amines and secondary amines.The predicted pK_a values were compared under different density functional theory(DFT)levels and basis sets,and the calculated result at the BP/TZVP level was in good agreement with previous experimental values.The predicted equilibrium ratio between carbamate and bicarbonate anions in CO_2-loaded aqueous amine solutions was used to evaluate the sorbent performance.Furthermore,DFT calculations in aqueous solution phases were conducted to study the mechanism of bicarbonate formation in the absorption of CO_2 with 2-amino-2-methyl-l-propanol(AMP).The results indicated that direct formation of a bicarbonate anion by the reaction of an amine,CO_2 and H_2O is the most probable mechanism instead of the hydrolysis of a carbamate anion.

关 键 词：胺溶液 CO₂吸收 量子化学 COSMO-RS模型 

分 类 号：X773[环境科学与工程—环境工程]