Abstract:

To solve the problem of too high energy consumption for the regeneration of carbon dioxide after the combustion of alcohol amine method, a method of adding metal ions to the amine solution to reduce the energy consumption of CO₂ desorption was studied, and it is called the metal ion complex thermal buffer self-heating utilization technology. Using the benchmark mono-ethanolamine (MEA) absorbent, we investigated two metal-ion additives [Cu(Ⅱ) and Ni(Ⅱ)] and revealed the mechanism of metal-ion mediated amine regeneration through the development and analysis of a chemical model of MEA-Me(Ⅱ)-CO₂-H₂O. It is revealed that in such system the metal-amine complexes act as chemical energy buffer to store the CO₂ absorption enthalpy and liberate it for CO₂ desorption, thus reducing the regeneration energy requirement. Comprehensive experiments of metal-ion mediated CO₂ capture process were performed to characterize the performance of CO₂ absorption and desorption, including heat of CO₂ reaction, CO₂ desorption rate, cyclic CO₂ loading, vapor-liquid equilibrium. The results showed that adding Cu(Ⅱ) or Ni(Ⅱ) into MEA increased the absorbent's cyclic CO₂ loading by 14%—20% or 7%—10%, leading to a reduction of CO₂ reaction heatby 6.6%—24% in Cu(Ⅱ)/MEA system and 6.0%—20% in Ni(Ⅱ)/MEA system.

Key words: carbon dioxide capture, absorption, metal ion complex, reaction heat

摘要：

为了解决醇胺法燃烧后捕集二氧化碳再生能耗过高的问题，研究了一种向胺溶液中添加金属离子以降低其CO₂解吸能耗的方法，称之为金属离子络合物热缓冲自热利用技术。以广泛商业化应用的单乙醇胺（MEA）溶液为研究载体，并在MEA溶液中分别添加金属离子铜或镍， 通过建立含有金属离子的MEA捕集CO₂体系的化学反应模型，解释金属离子热缓冲剂效应的内在机理。机理显示在MEA-金属离子-CO₂-H₂O体系中，金属-MEA络合物作为一种有效的反应热缓冲剂，将有机胺吸收CO₂过程中释放的反应热（放热反应）存储于金属络合物的解离键能中（吸热反应），在CO₂高温解吸中通过其络合放热反应将储存的能量释放出来用于CO₂解吸，形成自热再生低能耗CO₂捕集技术，从而降低了MEA再生的能耗。本文进行了综合的实验测定来评价金属离子对MEA溶液捕集CO₂过程的性能提升影响，包括CO₂反应热、解吸速率、吸收-解吸循环负载、汽液平衡溶解度等。实验结果表明铜离子或镍离子作为添加剂，能增加MEA的CO₂平衡循环负载14%~20%或7%~10%，同时能够降低MEA的CO₂反应热值6.6%~24%或6.0%~20%。

关键词: 二氧化碳捕集, 吸收法, 金属离子络合物, 反应热