离子液体对CO_2吸收性能的研究进展

Review on the research progress of CO_2 absorption with ionic liquids

CO2引起的气候变暖已成为全球最关注的环境问题之一,利用离子液体固定CO2引起了众多学者的关注。介绍了近年来离子液体吸收CO2的研究进展,包括常规离子液体和含氨基离子液体、氨基酸离子液体、聚离子液体及其他离子液体等4种功能化离子液体,并简要分析了吸收机理。综合分析了每种离子液体的吸收性能,离子液体对CO2的吸收能力均随温度上升而减小,随压力升高而增加。烷基链的增长以及含氟基团的增加有利于对CO2的吸收。功能化离子液体由于引入了功能化基团,相同条件下,其对CO2的吸收力几乎是常规离子液体的两倍。此外,将离子液体与有机溶液(特别是醇胺溶液)混合能提高离子液体对CO2的吸收能力,且能降低生产费用。最后指出了高吸收性能、低黏度、低毒以及低成本是未来离子液体的研究方向。

The paper is inclined to make a review on the research ad- vances of C02 absorption through the ionic liquids, including the con- ventional ionic liquids and the other four kinds of funetionalized ionic liquids, that is, the amino group-containing ionic liquids, the amino acid ionic liquids, the poly-ionie liquids, etc. In the paper, we have also made a brief discussion and analysis of the mechanism of the ab- sorption and the absorptive properties of each type of the ionic liq- uids. In addition, we shall discuss the absorptive power of C02 for its advantage that its absorptive power decreases with the increase of temperature and pressure. As we know, longer alkyl chain and the fluorinated group are beneficial for increasing the absorption of COz. Due to its structure of the basic groups, it is easy for the amino group-containing ionic liquids to absorb CO2. Besides, since the amino acid ionic liquid consists of natural amino acids, its derivatives enjoy high biodegradability and environment-friendly nature. More- over, as hydrogen enjoys high bond feature to the amino acid, it is easy to make the ionic liquid dissolve CO2. However, so far we know, little progress has been made in the studies of the polymeric ionic liquids due to the high cost for its development, to be exact, under the same condition it would almost cost twice as much as high to absorb CO2 by using the conventional ionic liquids with the func- tionalized ionic liquids. What is more, the functionalized ionic liquid also proves to have more advantageous regeneration properties, though the research on it still remains in the stage of synthesis in the laboratory condition, the cost and the viscosity of which remain higher than by using the conventional ionic liquids. Besides, the ionic liq- uids mixed with organic solution, especially with alkanolamine, can not only help to heighten CO2 absorption capacity, but also reduce the production costs. Therefore, it can be concluded that there will he a great prospect and potentiality to develop the ionic liquids with high absorption power, but low viscosity, low toxicity and low cost in the future.