Abstract:

Alkanolamine-based chemical absorption is efficient and convenient for CO₂ capture. However, the practical application of this technology is limited by high energy requirement of regeneration. Two methods of regeneration were presented based on the reaction mechanisms and characteristics, namely thermal regeneration with non-aqueous solutions, solid acid catalysts and nanoparticles, and chemical regeneration with calcium ions. The analyses showed that different kinds of amine would give different products which were related to the free energy for regeneration. Therefore, it is a necessary to choose suitable amine or amine mixtures. Ethanol, a common nonaqueous solvent, is able to reduce the demand of heat of desorption through decreasing the sensible heat and heat of vaporization. Besides, the reaction time and temperature could be reduced by optimizing the Br?nsted acid sites and mesoporous surface area of solid acid catalysts. Furthermore, the use of nanoparticles is able to enhance heat and mass transfer of solutions, resulting in heat duty reductions during regeneration. But further research is needed to confirm the reinforcing effects for amine solutions. Chemical regeneration with calcium ions was found to reduce the cost of regeneration largely and showed promising potential in industrial application. Moreover, further decrease in the cost could be achieved by improving the homogeneity of fly ash.

Key words: carbon dioxide, desorption, alkanolamines, low energy consumption, regeneration

摘要：

醇胺法吸收CO₂具有效率高、易改造等优点，但较高的再生能耗严重阻碍了其实际应用。本文在介绍醇胺吸收机理和各种醇胺的解吸特性的基础上，分析了采用非水溶剂、固体酸催化剂和纳米颗粒等方法来降低醇胺富液热解吸能耗，以及采用钙基化合物对富液进行化学解吸的原理及可行性。分析表明：再生热负荷与吸收产物密切相关，选择适合的醇胺吸收剂可降低再生反应自由能；非水溶剂在降低显热和汽化热方面效果显著，利用乙醇吸收产物稳定性低的特性，能在降低显热和汽化热的同时降低解吸热；优化固体酸催化剂的中孔比表面积和B酸酸位点或制备新型双功能催化剂能缩短加热时间和降低温度；纳米颗粒通过提高溶液传热传质效率减小再生热负荷，但对醇胺传质传热效果还需进一步研究；采用氯化钙和氢氧化钙等钙基化合物解吸富液成本低、效果好，通过改善粉煤灰等含钙工业废料的均质性和有效成分占比，化学解吸成本有望进一步降低，具有广阔的应用前景。

关键词: 二氧化碳, 解吸, 醇胺, 低能耗, 再生