基于有机胺的化学吸收法是燃烧后CO2捕集行之有效的技术之一。然而，传统有机胺法的高再生能耗使其工业推广及应用受限。为降低CO2捕集能耗，相变吸收剂应运而生。该类吸收剂吸收CO2后由均相变为互不相溶的两相，CO2主要富集于其中一相，仅需分离CO2富相用于再生，即可大幅减少再生体积进而降低吸收剂捕集CO2的再生能耗。相变吸收剂包括液-液相变吸收剂和固-液相变吸收剂，后者的CO2吸收产物能以固体形式从溶液中沉淀析出，可实现产物快速分离，成为近年来相变吸收剂的研究热点。根据吸收剂的组分构成，固-液相变CO2吸收剂主要可归为3类：有机胺非水溶液、盐溶液和离子液体固-液相变吸收剂。有机胺非水溶液以有机胺作为吸收活性组分、有机溶剂充当相分离剂，具有吸收速率快、腐蚀性小的优点，但其吸收CO2后固相产物易形成黏稠胶状物且再生较困难；盐类固-液相变吸收剂主要包括氨基酸盐和碳酸盐水溶液或贫水溶液，具有成本低、原料易得的优点，但现有盐类相变吸收剂的固-液相变特性及相分离效率有待进一步改善；离子液固-液相变吸收剂主要有常规离子液（溶剂）/有机胺（活性组分）和功能化离子液（活性组分）/有机试剂（溶剂）2种体系，具有热稳定性好和再生效率高等特点，但离子液体合成较复杂且使用成本较高。总之，相比于传统有机胺吸收剂，固-液相变CO2吸收剂具有较大的节能潜力，有望为高效低能耗的CO2捕集提供新的选择。目前固-液相变CO2吸收剂的开发还处于试验研究阶段，要推动其实际应用，今后的工作应侧重于吸收剂的构建方法、相变机制、热力学、动力学及工艺优化等问题的研究。

Chemical absorption based on organic amine is one of the effective technologies for post-combustion CO2 capture. However, the high regeneration energy consumption of the traditional organic amine process restricts its industrial application. To reduce the energy consumption of CO2 capture, phase-change absorbents came into being. This new class of absorbent can change from homogeneous phase to two immiscible phases after absorbing CO2, and CO2 is enriched in one phase. Since only the CO2-rich phase is separated for regeneration, the regeneration volume can be greatly reduced and the regeneration energy consumption of CO2 captured can be significantly reduced. Phase-change absorbents include liquid-liquid phase-change absorbents and solid-liquid phase-change absorbents. The latter absorbs CO2 to form solid precipitate that can be rapidly separated from the solution, which has become the research focus of new absorbents in recent years. According to the composition analysis, solid-liquid phase-change absorbents can be classified into three categories: organic amine non-aqueous solutions, aqueous salt solutions and ionic liquid-based solutions. Organic amine nonaqueous solution uses organic amine as the absorption active component and organic solvent as the phase separation agent, which has the advantages of fast absorption rate and low corrosiveness. However, after absorbing CO2, their solid products are prone to form sticky gel and difficult to decompose. The salt solutions, which include amino acid salt and carbonate aqueous solution or water-lean solution, have the advantages of low cost and easy availability of raw materials. However, the solid-liquid phase-change characteristics and phase separation efficiency of existing salt phase-change absorbents need to be further improved. The ionic liquid-based solutions include two kinds of systems of conventional ionic liquids (act as solvents)/organic amines (act as active components) and functionalized ionic liquids (act as active components)/organic reagents (act as solvents), which have the properties of good thermal stability and high regeneration efficiency, but ionic liquids are complex to synthesize and their cost is relatively high. In a word, compared with traditional aqueous organic amine absorbents, solid-liquid phase-change absorbents have a greater energy saving potential and can be expected to be a promising alternative for CO2 capture with high efficiency and low-energy consumption. At present, the development of solid-liquid phase-change absorbents is still in the stage of experimental research. To promote its practical application, the future work should focus on the design principle of absorbents, phase-change mechanism, thermodynamics, kinetics, and the optimization of CO2 capture process.

0 引言

1 化学吸收法捕集CO2工艺

   1.1 传统有机胺捕集CO2工艺

   1.2 液-液相变吸收剂捕集CO2工艺

   1.3 固-液相变吸收剂捕集CO2工艺

2 固-液相变吸收剂捕集CO2

   2.1 有机胺非水溶液固-液相变吸收剂

   2.2 盐类固-液相变吸收剂

   2.3 基于离子液体的固-液相变吸收剂

3 结语与展望